Caterpillar D2/D4 Starting Engine: How Much Compression Should They Have? Let's Test a New One!

[@tonyrum5808]

Your PhD in Caterpillar products is warranted and appropriate. Your expertise in CAT is well known and acknowledged by everyone except the Caterpillar Corporation. You have my endorsement and appreciation for your hard work and dedication to the heavy beasts you rebuild, service and enjoy. All the best to you Toby keep up the excellent work even though you are unsupported by the product you serve!!

[@Pamudder]

75 PSI amounts to 5:1 compression, which in the 1930's was pretty standard even on fancier automobiles. The gasoline then available for automobiles wouldn't tolerate anything higher. It wasn't until after World War II when refineries that had been specially constructed or adapted to produce 100-octane aviation fuel for the military started producing higher-octane fuel for the civilian market.

[@paulcopeland9035]

5:1? There is nothing "standard" about compression ratio. Compression is a function of combustion chamber volume. Oh, and by the way, tetraeythel lead was "the" fuel additive octane adder, developed in the "1920's" to allow higher compression engines to be built! The above comment speaks to the problem our country is having these days. Facts don't mean shit any more. Sad!

[@PEThurman]

I appreciate your approach to maintaining older equipment! Thank you for taking the time to explain what you do and your reasoning behind what you do for maintaining antiques!

[@stephenmcfadyen1385]

For people without your knowledge of how an old engine is manufactured is priceless, folk who purchase an old machine just for the fun of having one and occasionally run at home or at shows should be guided by your advice. The older dozers we had in our felling business were often on sold to enthusiasts and our mechanic would go into such detail to the buyer on how to best lubricate the running components for best continued life. Great tutorial.

[@andrewlindh5047]

What helps is the explanation of why you made these choices and how it works for the engines you run and what happens with the oil and procedure you use. This is not normal advice of "Use this oil, it's the best" but an set of reasons for your choices of what and why so we (the common people) can apply your experience and expertise to our own situation. The best advice helps me make my own decisions! Thanks! Also, WOW that's a lot of iron in that oil for less than an hour of use.

[@AirDirectLLC]

Love watching your restoration and the attention to detail. It was great to see the starting process of a fresh rebuild.

[@mikewednesday8541]

Interesting to see the suspended metal particles picked up by the magnet. My philosophy on the old starting engine is that I will take the time and expense to change the 1 qt. of oil every few starts and do all I can to prolong starting engine life. Thanks for another informative video👍🏼

[@geoffmorgan6059]

@@squatch253 Your comments about non-detergent and detergent oil are spot on. Oil company advertising (mostly past but some present too) is responsible for most of the confusion about types of oil. Of course, today, "synthetics" rule the roost. The days of engines without filters are gone for the most part and non-detergent oil is getting to be difficult to find. You will probably be getting arguments about paraffin based oils vs. asphalt based oils. Just something else to argue about. Unless you have a 50 year old unopened can of Oilzum or Pennzoil in your cabinet, you don't have any paraffin based oil. Again, thanks for your unbiased and correct information on oil applications!

[@cydery]

Surprised there's no magnet in the sump plug??

[@gregoryschmitz2131]

Frankly I would like to see more engine oil talk. What was right for the old machinery is not the same as today. I worked on a Dutz Air cooled (diesel) engine and we estimated it had 8-20,000 hours and going good. Those engines had a strainer not a filter and the oil change was 50 hours. Sometimes it got changed and sometimes not (out in the Philippines at Clark and the military maint people they paid to maintain it were conscientious to totally slack) . That was with a fairly modern oil (80s era)

[@lukestrasser]

I almost asked on the first start video if you were going to perform an early oil change, I now know without even asking. The way I look at it, oil is cheap, rebuilds are expensive. I’m also a fan of running detergent oils, more for the additive package than the detergent/suspension capabilities. ND oils usually have a weaker additive package from a anti-wear/extreme pressure protection. However, like you said, everyone has an opinion (that is always the correct one) on which is better. On that note, I’m extremely cute see what the oil analysis says on Kyle’s RD-4 engine and back end, it’s a look back in time to see what they were using in the 1970s! Cheers!!!

[@colin8532]

Wow, that's pretty cool. I still can't get over just how black that oil is after such a short run time. Your explanation makes a lot of sense though, thank you. Oh, and I see what you meant in a video a long time ago, KZbin really does pick a thumbnail with your mouth open! LOL

[@KennyKizzleRustyNutzRanch]

Great info on break ins and engine oil use. Looking forward to the next segment!

[@wazza33racer]

once the break in is done, run synthetic. The reduced friction it provides, makes a vast difference, provided oil change intervals are kept the same.(dont extend them). I have hundreds of hours on small engines that run like new, with no appreciable wear. Same is true right up to heavy truck engines that cover 2 million km's, 100% full loaded on 65 ton B-doubles.

[@jrevillug]

Good oil discussion! I wouldn't go putting detergent oil in a well-used pony motor though; it will likely have that build up of sludge and once there that's better left alone until rebuild.

[@timstouder5149]

Well you're very informative again ! My dad always told me to put non-detergent oil in lawnmower engine but I never knew why & I didn't know the difference, just did it . so you taught this old dog a new trick .

[@danielbutler578]

Back in 1980 I tore down a locked up 390 Ford engine and did a rebuild on it for my brother. It used a quart of oil in its first 500 miles and gradually decreased its oil consumption during the first 6000 miles. He was all upset about his fresh rebuilt engine using oil until I explained to him that it would need to be driven enough to get through its break in period. After the second oil change it would go 6000 miles and only be a little below the full mark.

[@peterfallert4994]

Looking at a D2 to possibly buy. Pros. 15 miles from home. Well maintained. Unaltered (not a bunch of home made repairs and add ons) Cons. Doesn’t run. Possible cracked block. Has been sitting for 20 years. Need advice on parts availability and sources. I don’t know how to communicate with you other than the comments section. You probably don’t have time for individual responses. Thanks, Peter

[@peterfallert4994]

@@squatch253 Thanks for your informative reply. I did watch your video on assessing a D2 for possible purchase. It just fortified my interest in getting a D2. If it turns out to be too costly to repair, is parting out an option? My background is, former Detroit diesel technician worked on the 12V 149s down to the 53s. Former Mercedes Benz diesel tech. Retired Toyota master tech. Have a shop with lathe and milling machine, gas, arc, and mig. Bought my first car when I was 13. Restored cars, but tired of bodywork, wiring, glass work, upholstery, painting, etc. Looking for something purely mechanical. Never worked on a Cat, but the D2 fits the bill. Thanks Peter

[@NinerFourWhiskey]

We run-in new and resurfaced aircraft cylinders with mineral oil (non-ashless-dispersant) for this very reason. The rings wear the hone surface down for compression and leave just enough surface to hold oil. Aircraft engines in the old days didn't even have filters, just screens! 2 hours first run, 10 hours next change, then 20 and usually by then, we switch to ashless dispersant oil.

[@woodwelder]

Can’t beat that logic !! Couldn’t get over the colour of that oil …. ! Prevention is better than cure ! The oils these days are 100 times better than in the day ! And your rebuild was so precise - it will see us all out ..!

[@michaelmathews295]

Some builders don't put oil on the pistons or cylinder walls during reassembly, running them dry so it breaks in faster. I never did it with anything I rebuilt but I'm probably too chicken to risk it.

[@MetallicAH2O]

Great job and video @Squatch253. I think the main take away is to service your stuff!! I had a trade school teacher who would always say, "Any oil, especially clean oil, is better than no oil".

[@larrywalker7759]

Another aspect of compression is that compression is dependent on how well the rings "inflate" during the compression stroke. The rings are not sealing themselves against the cylinder walls and the piston ring lands simply because they "fit so tight". The rings also react to the displacement of the air charge during compression by inflating to press hard against the cylinder walls and the ring lands of the piston. That is why an engine in a vehicle that has not been run in a long time may have poor compression in an initial compression test but retesting later can show improved compression after the rings have freed up. Likewise the ability for rings to inflate can be affected if an engine is subjected severe overheating and the elasticity of the rings is reduced and the rings can warp slightly. Of course in overheat events you have a lot more to worry about than if your rings are going to survive.

[@mikes1345]

My first car was a 61 chevy with an unfiltered 235 engine. It dripped a quart a week from the rear main. It used rerun oil for a while. When I rebuilt it I found an oil filter at a wrecking yard to bolt on manifold. Took me several tries to route the connecting hoses so they wouldn't rub a hole in them. I did change to a premium oil after rebuild but I never could keep old chevys from developing slow leaks in rear seals until I got into 70s model engines. Even our 36 massey harris tractor used oil pretty regular so adding oil is what my brothers and I did constantly. I cringe when the dealer says my new car only needs oil change every 8 to 10k.

[@davidmcd8400]

Even though you can wait until the computer says change the oil I still change it and the filter at 3000 . 4000 tops . Oil is cheap .

[@raycollington4310]

This information is an eye opener. No-one does break-in oil changes on new cars in UK. Accepting this is old technology, this makes me think a break-in oil change is a must. The channel keeps getting better Squatch, you've single handedly turn us all into Cat D2 experts.

[@nerd1000ify]

Most modern cars have the 'break in' done at the factory during machining, it's called a 'plateau hone' and basically uses a special abrasive brush to smooth out the initial hone pattern in the same way the piston rings do in a traditional break in. The piston rings are similarly manufactured to a greater degree of precision so that they can seat against a plateau honed bore without needing to be run in. The engine will still 'run in' to a certain degree, but it's like 95% of the way there before the engine is started for the first time. Just to add to the complexity, some manufacturers have stopped using cast iron cylinder liners, instead the aluminium bore is coated with a composite material made of silicon carbide and nickel. The silicon carbide component is harder than sapphires, and under most circumstances won't run in at all- a fine diamond hone is used to remove a thin layer of nickel and expose the silicon carbide, at which point the cylinder is complete, with the low spots where the nickel was removed acting to hold oil like the crosshatch in a traditional cylinder. Only the rings get broken in.

[@raycollington4310]

@@nerd1000ify Thank you your insight and this very comprehensive reply.

[@lrrromicronpersei8294]

I know people get feisty about oils and types and changes etc everyone has their own ideas and preferences I don’t judge anyone on their choices, but I do find it interesting to know what other people do, Keep up the great work and thanks for bringing us along for the ride… Will I ever own one of these beautiful beasts i very much doubt it but I do find it interesting So thank you

[@edwinhsingmaster9135]

Well on that note, my guess is your next oil discussion will not include the additives "zinc" and "phosphorus". You can't make that horse drink, no matter! Keep up the good work.

[@abraxasracing]

After watching all the pony motor videos and the oil discussion, I'm fairly sure that the reason my grandfather's D4 was parked on a steep hill most of the time and there were several pony motor blocks lurking in the shed is because he didn't change the oil in it much and always shut it off with the magneto...

[@johnscott8221]

Well personally I think you are a great mechanic. I’m just working on a Farmall B. But your explanations make so much sense and challenge me to think.

[@jerryderouin9987]

Hi Squatch you have done a really fine job overhauling this tractor,and as long as we are talking about oil, how often do you change the oil on on your equipment ,I realise after all the time and money you have invested in this D2 you will want to take extra good care of it but what about your equiment such as the RD6 and the other equipment witch you seldom use!!

[@thomasbailey8306]

That detergent oil is a good Idea doing it like you do Squatch. Good idea for sure.Great video...

[@jondavidmcnabb]

That is insane! I do small engine repair all the time and routinely hit 120. You should talk about this extensively and why and what are the advantages.

[@DaveWilliamsj]

I would not want a higher compression as it can have quite a kick back as it is.

[@larrydavidson3402]

Very informative video, the amount of metal on that magnet sure surprised me.

[@allanrichards3752]

As for compression I once restored a Lister CS diesel engine. These have a chrome bore (Listard cylinder) which was seized solid. I had to bash hell out of the piston to remove it but the chrome bore looked ok after a light honing. I put new rings in but had no real compression to start it. I coupled it to another engine and span it over until it started. Much like the pony motor arrangement on the Cat. After 4 hours running it had really good compression. Again no filter but I changed the oil regularly. It only took a little oil so why wouldn't you. Also if its sat for a while in a cold damp shed the oil might pick up water which isn't good.

[@wilmamcdermott3065]

Basicly u turn cylinder walls into a micro file for the rings wich have groves desighned to wear. To a smooth finnish and conform to the shape of the cylinder walls

[@thesearcherman6652]

@@squatch253- When questioned years ago on the phone about less zinc in modern oils, and older cars needing higher zinc levels, Mobil told me that their zinc replacement additive packages were superior to zinc. I tend to believe them. Moving camshaft and lifter production to China and Turkey, well guess what, they sent improperly hardened camshafts and lifters to cam grinders who then sent them to the engine rebuilders. And, to make more power requires a more aggressive camshaft profile, plus stiffer valve springs than stock. The whole zinc thingy is likely a pile of bull shit. The real issue is higher performance and Chinese and Turkish junk. Translated: money. It’s not really cheap nor easy to harden a camshaft lobe correctly.

[@seniorelectrician6831]

Excellent explanation. I hope to get to the upcoming meet on Friday. I have a appointment in the cities on thurs afternoon, and trying to talk the wife into going there then to Eau Claire.

[@seniorelectrician6831]

@@squatch253 pioneer power swap meet,

[@davidschmidt1780]

Very informative I couldn’t agree with you more about your reasoning and theories fresh oil is cheap insurance !

[@PRRGG1]

Dangerous territory Toby. "Tastes great / Less Filling" "coke / Pepsi" "flame broiler / fried" "Maryanne / Ginger" "Ford / Chevy" boy oh boy, can opened, worms EVERYWHERE!

[@joshua89schultz]

Very good method to your madness squatch, at this point you have proven yourself and if you told me to run vegetable oil in my machine I probably would ha ha. Thanks for another informative video, cheers.

[@obryan240]

Just had your channel pop up in my suggestions. Guessing from your screen name your local to me in peirce county.

[@SuperMAZ007]

Thank you Toby for the insight, there was some valuable info in this video for me. I can't comment much on the oils cause I use very different brands to what your using. So I don't wanna start a fight here. However I will say this people do make mistakes when the break in diesel engines. Main mistake I have seen is when people break in the engine and don't follow the factory recommendations. This is when things get messy and you get engines that spit out oil or the rings don't wear in correct. Ask me how I know :D

[@ron827]

Oh no, if you are using Pennzoil in that pony engine, it will be ruined by June because my wife's hairdresser's brother-in-law had an engine fail using Pennzoil. :-) Good info on changing the oil in the rebuilt and that compression is IMPRESSIVE.

[@bigtrev8xl]

🤣😂

[@BobPegram]

Squatch253, you deserve so many more subscribers!! That said: What about Diesel engine oil? Will you get to thst topic too? If so, about when?

[@brjr2009]

Maybe you could engineer some kind of filtration system for the break in oil. The detergent package is no where near depleted. Then the oil that is getting expensive and harder to find everyday could be re used in the break in. Just a thought.

[@keithross4511]

Pony motor is a happy camper and great information!

[@kevinschroeder3889]

Thinking ahead to warm weather. How big is the building going to be that you're going to build this summer. Might have to join the members group as way of helping fund it.

[@dans_Learning_Curve]

Always learning something from your videos!

[@woodhonky3890]

Spot on about initial oil changes in new (or rebuilt) small un-filtered engines. It is amazing how much more life you can get out of them by the method you described.

[@horatiohornblower868]

Caterpillar ought to give you an honorary degree in mechanical engineering, Toby!

[@wilmamcdermott3065]

Any time u do a rebuild Never use a synthetic oil so you do get an engine break in

[@jacquesblaque7728]

Being a big fan of KISS, every filter-less small 4-stroke I have has a permanent magnet epoxied onto its dipstick. The rate of accumulation of shiny fuzz there drops noticeably during the first dozen or so hours of runtime. I refuse to passively let that stuff loose in there, when I can trap it- never heard of benefits from it getting between cam lobes and followers, and that sort of thing.

[@btomlin5764]

I guess everyone can argue about that all day long about the oil, but you can bet your bottom dollar, if I was rebuilding one of these things, it would be the "Squatch" way. Period.

[@brycewiborg8095]

I had a 48 VAC Case without a oil filter. Turns out the oil filter was a option.

[@lapoint7603]

Squatch is the Oil Guy!!

[@scrotiemcboogerballs1981]

Wow I wouldn’t have guessed there was that much metal in the oil for that short of a run thank for sharing buddy

[@ImpHalla66]

The wife is always asking what perfume to buy. I say "90wt or 92 octane". (a comment about oil)

[@KG-yn9qi]

As an another up grade. Is there a spot on the block low where could drill a hole and tap it . For a plug, that could extend into oil . Like a drain plug with a magnet. You could take out and clean to help catch debris?

[@krinkofski2276]

If it never had an oil pump it wouldn't have any oil passages to accommodate oil circulation. My mistake. Thanks for the replies.

[@MrGTOFixit]

Ok, Squatch I'm impressed with the compression check, but at 1min33sec you switched to the gauge view now in impressed with that valve on the floor WHAT did it come out of WOW,

[@anibalbabilonia1867]

Wow! Amazing how much metal particles can come out of those pony motors! Looks great though!👌😎👍

[@cdoublejj]

i learned a lot. maybe you cna explain the pros and cons of parfin based oils?

[@wemedeeres4105]

The only thing that could make the oil topic more controversial is to throw different viscosities into the mix!

[@Hyratel]

10w30, 10w40... It stops making a difference below a certain size and fineness of engine. Is is it to the line ? Is it not black as your grandads coffee? You're just fine

[@jeffreykull4676]

good info i always was wondering about that. seen the last video it sounds good.

[@darrenhawken9766]

Thanks for sharing your knowledge 👍

[@alanbare8319]

Would have possibly gotten a higher reading if you had pulled the spark plug from the other cylinder? It looked like you had the spark plug still installed in the other cylinder.

[@mikebaldwin9972]

I want to know‘Are we Happy with the way it’s running “ ?????

[@KG-yn9qi]

Guess easy to arm chair ideas when do not have a dog in the hunt!!! So what about Bork!?? He going off the deep end or what? Think his best pals Mr. Bud and Wiser are getting the best of him? Know not my place to say… but just like the guy and like to see him do well!

[@thegreatchickenoverlord5976]

> oil The most dangerous topic to ever discuss in any tractor or equipment forum.

[@bigtrev8xl]

🤣🤣

[@darylullman7083]

Good info here. But, I'm curious about the valve sitting back there on the floor.

[@gregstapp1684]

the four things you never mention in a public setting ... Religion , Politics , Oil and which manufacture makes the best trucks 😆😁👍 and for that matter the proper color of tractor ... thanks @squatch253

[@timothyball3144]

Confirmation bias is a real thing; therefore, I won't argue with your opinion on oil.

[@AIM54A]

Is a modern break in oil with ZDDP of any use here?

[@ronniewalker2881]

good video good content keep up the good work ethic

[@dans_Learning_Curve]

*OIL* Yes

[@evankibbe590]

When I was working on generators I would tell the people running the using them that I wanted them to change the oil every 2 tanks of gas ⛽!! And they would say we're supposed to send a sample in !! And I would say I don't care what you are supposed to do! This is want I want you to do because by the time you get the results back it will already be blown up!!!!! And because I'm in charge of them !!! And I would tell the people that couldn't keep them running not to put diesel fuel in them and not to check the oil when running!!! Because they would eat the dipstick!!!! FACT EVERY TIME !!!!

[@davidpierce3386]

So Toby what did Caterpillar advise/ suggest for break in procedure for a rebuilt engine with new rings, ground valves and seats, and or lapped in valves? I've had small block chev engines that suggested 500 miles which I believe is 10 hours of running. Either way, IT IS ALIVE!

[@amandagirl8042]

could you not hook a drill up with a socket to fit the crank pulley to roll that starting engine over? like the project farm guy does to start lawn mowers

[@amandagirl8042]

@@squatch253 says the guy who builds a tool for everything lol

[@amandagirl8042]

@@squatch253 it would make a good video of you going threw all the tools you made to over haul 1113

[@charlescastle5566]

Squatch, I guess I'm going to be the one to ask I've done several small engines. How do you feel about going synthetic after breaking in with dinosaur juice with zinc? No arguments from me just asking.

[@robertrowse1028]

What is your opinion on magnetic drain plugs?

[@petebrooks6539]

This may be a ticklish subject, but what are your feelings both pro and con about Frantz filters, (the ones with TP). I have seen demos where they will take water (or coffee) out of oil, but do you think there is a harmful side to them as long as they have a bypass in them?

[@paulsalb1686]

Just wondering how do you really feel about an IDI

[@zakksrage]

My 5 year old harbor freight gauge won’t leak down a lb

[@Denis-tu1pd]

You can never change oil enough.

[@oldamericaniron5767]

I always believed the best oil is clean oil and full level. After listening to your talk on nondetergent oil I will be getting some for my Sixty before start up. I’ve also heard of low ash oil, what do you know about that?

[@nerd1000ify]

Newer diesel oils are 'low ash' basically this means there are lower limits on the concentration of calcium, sulfur and phosphorous in the oil because those elements will not burn in the exhaust particulate filter (aka DPF). Using a high ash oil in an engine with a DPF might cause the filter to get blocked and need chemical cleaning or replacement. The downside is of course that those elements are found in many popular detergents and anti-wear additives, so the oil is less effective at preventing sludging and wear. You'll also see 'low ash' or 'ashless' labelling on 2-stroke oils. Because 2-strokes (attempt to) burn all their oil, any ash content will tend to form combustion chamber deposits or block the exhaust port, especially in water cooled engines.

[@jimmotormedic]

Bottom line, no matter what oil costs it will always be cheaper than the engine it used in

[@lorenblanchard4348]

Thanks for the oil insight. On these old engines (both diesel and gas), do you add zinc to the modern oil to soften the lifter/cam contact and other wear points?

[@MichaelTJD60]

The high ZDDP content of today's diesel oils and low-ash oils is specifically for engines with flat tappets - so there usually isn't a need to add more zinc. As Squatch and a few others have said in the comments, most modern oils are superior to what was around when these engines were designed, so they already have most of the bases covered.

[@otm646]

@@MichaelTJD60 You're about 10 years behind the times. The new diesel oils have had a significant reduction in zinc because it's damaging to the diesel exhaust catalysts. You'll find endless threads on this topic at Bob is the Oil Guy and on TDIclub. Even the older spec diesel oils have reduced their zinc content.

[@MichaelTJD60]

@@otm646 exactly why I drive a 7.3 Powerstroke...CJ-4 and older oils are my specialty.

[@eduardslootweg2973]

Good day ….. where can I find parts for a 1958. 933 Traxcavator steering clutch?,, hopefully you can help me Love Your channel Ed

[@scotcoz]

Ok so when this done and everything is up and running. What is a it worth ? What do they sell for. Or where do you look to find a price? Thanks

[@drewscruis]

Apologies in advance of you answered this already, but did you run a high zinc oil in the starting engine?

[@Drottninggatan2017]

Keep a magnet permanently in the sump. Like they do in gearboxes and final drives. By the way, the black in the oil is soot. It comes from the combustion.

[@michaelbaumgardner2530]

You were on the edge of no mans land...Lol

[@HillbillySailor]

Do you run a zinc additive in your oil for better flat tappet cap wear?

[@aw738]

At 1:30 on the left of the screen. What is that valve out of?

[@Recommended_by_Fred]

I have a more technical question, my pony engine has a straight out spark plug. I believe it has a smaller combustion chamber. I think I seen a tech bulletin about changing the heads and adding more RPM for the D4 engines. I wonder how much more compression that would give one?

[@Recommended_by_Fred]

@@squatch253 there was a TSB ( you remember those haha) that I read about changing the heads and slightly increasing the RPM. It was aimed at the D4 in cold climates. I will see if I can find it. It was in the caterpillar service magazine articles.

[@dudleycornman1624]

You are kind of turning the rings and cylinder walls in to weak files...

[@chuckhaynes6458]

Magnetic drain plug.

[@elijohnson182]

You just have to use your brain when it comes to engine oil.

[@Titan604]

One tip I have heard for engines with no filter is to magnetise the dipstick. Then every time you check the oil, you wipe the dipstick removing the iron particles that have stuck to it.

[@loisgunstone8444]

Where possible l bore a hole in the drain plug and fit a piece of bar magnet to it.

[@paulmanson253]

Or glue a magnet to the end of the drain plug.

[@chrishanes4310]

I must have said, "WOW" six times after you showed the magnet. Amazing how much cast iron can wear like that. Thanks for the tutorial!

[@culturaldivide6817]

Any of the Facebook groups I'm in if you start talking oil's people heads explode.....

[@ajsfarm8553]

When will your next up load be?

[@clydeschwartz2167]

Excellent video you are absolutely right about the oils. I have broken in big diesel engines with non detergent motor oil. I have also used non detergent motor oil as a flushing agent in really dirty engines before I take the oil pan off it does a good job of scrubbing the sludge out I bought a G705 mm diesel tractor years ago the oil was so thick and nasty it would not drip off of the dipstick in 90 degrees weather so I flushed it a few times and the oil started staying clean. Every type of oil has it's place depending on the purpose. Keep up the great videos Toby