What Kind of Oil Should I Use?

What Oil Should I Use?

by Francis Robinson

I keep seeing this question pop up over and over again in discussion groups all over the web. As with many things there are often several right answers and a few wrong ones.

Some purist I'm sure will disagree to no end with what I will tell you but most of us out here in the real world don't really care do we ? Some of them only bring their noses down out of the air long enough to look down them anyway. If you are like me you are only doing this old tractor stuff because you enjoy it. You will find that in general, "old tractor" buffs are a great bunch of people and more than willing to help you any way they can. I would give you a brief warning about advice from someone who may be more of a novice than you are, if possible get several answers and "average them out". Most discussion group answers are really good but I have seen a few where their "BS" didn't indicate a college degree.

On to the slippery subject, one reason I mentioned the purist is that the lubricants called for in most old tractor manuals were simply the very best recommendations they could make at the time of manufacture and many of the products we have available today just didn't exist. Had todays products been available then, not only would the manufactures have recommended them, they would have been thrilled by todays quality.

"Can I use detergent oil in my 1945 Farmall "?

Of course you can ! In fact if you don't, I may have to come by your house and smack you up the side of your head with a board ! Very early detergent oils had a few problems but those were eliminated over forty years ago. ALL four cycle engines in normal use today should be running with detergent oil. Yes even lawn mower engines. Non detergent oils belong in your oil can. The detergent helps to keep the contaminates in suspension in your oil so they drain out when you change oil. I have farmed for many many years and have operated businesses repairing automotive and small engines and I have always been amazed at the number of "old wives tales" that otherwise intelligent people in the business buy into.

"Joe Blow said if I put oil made for a diesel in my gas engine it would ruin it".

Nonsense ! Forget what Joe's grandmother heard at the quilting bee and think a minute. Do not diesel engines and gasoline engines both use basically the same pistons, rings, rod and main bearings ? Does not the oil perform the same function of lubrication and cooling in both ? Now for the clincher, in case you have not been watching, do not the oil companies now rate their premium oils for both services as well as turbo service ? Your gas engine has a compression ratio of anywhere from 5:1 to 8:1 while a diesel engine runs from 13:1 up to 18:1 and so needs to use only a premium oil to protect it better. The diesel service oil also needs to be higher detergent in order to suspend the carbon particles inherent to their operation. Turbo approved oils must be tough enough to hold up in the extreme temperatures and ultra high shaft RPMs inside the turbo charger unit. Don't let "Joe Blow" tell you it will harm your old tractor. Buy the best and change it often, it will save you money.

"My Allis Chalmers "C" calls for 20 weight motor oil in the transmission and differential, but it is really noisy".

This also applies to several other tractors as well. Back when they built these, the old standard 90 weight gear lube wouldn't flow thru their tiny little pistons and valving of the hydraulic pumps at anything cooler than a summer day, thus the motor oil. Even the old 30 weight oils got pretty stiff when cold and the automatic transmission fluids available then would never have been enough protection for heavy pulling, plus they were prone to excessive foaming. Due to todays better oils, that motor oil recommendation is safer than it was back then but I changed all of mine years ago to the newer "universal trans-hydraulic" oils which are compatible with such lubes as Massey-Ferguson "Permatran" or John Deere "Hy-gard" and many others. I also used it for years in a backhoe and other construction equipment. One side benefit of using it in all hydraulic systems is that I can change equipment from tractor to tractor (I have 9 in use) with out worry that I am mixing different types of oil due to oil still in remote cylinders.

"The book says to only use their brand of oil".

I would say that too if I was selling oil. Don't buy dimestore oil, and check the label for ratings. If you don't have to worry about mixing oils go ahead and buy the factories brand of trans-hydraulic oil, it doesn't cost that much more. I have always preached that buying ultra-cheap oil is the most expensive money you can save. On tractors with out combination systems I still use regular gear lube for transmissions, differentials and final drives and the trans-hydraulic oil in the hydraulic systems.

Steering gear boxes are another matter, I have several tractors with out power steering so I like to use some kind of "super-lube" such as Slick 50 or Duralube. It really does make them steer easier. Here is a simple "cheap skate" tip (muzzle yourself purist), if your steering gear seals leak badly and won't hold oil (common) and you don't have the time or money to rebuild them now, put a grease fitting in place of the plug and buy a tube of Slick 50 grease, it works fine. Ok, release the purist.

There isn't room here to cover how much or where to drain or fill each model but there are a few common sense guidelines to go by. Engines always have either a dipstick or a petcock to check the oil level, DO NOT OVERFILL. Transmissions and differentials typically have a oil level check plug about 1/3rd of the way up on the side of the housing. They get filled through this or a larger plug up on top, but take the side plug out to avoid overfilling. The drain plugs are on the bottom (duh !) but you might need to remove several in order to drain all of the separate compartments. As a rule of thumb gear oil levels are kept below the bottom of any horizontal shaft which runs through an opening with seals and depend upon the gears to carry the oil up to the shaft bearings. Final drives normally run with just a few inches of lube which is carried up by the lower gear to the upper. These are often badly ignored.

If your tractor does a lot of hard work like bush-hogging you might want to see if you can install an oil filter in the hydraulic system in some non destructive manner. I have a couple of Farmalls that use the hydraulic oil for the power steering so I have a filter in the power steering return line. Never put a filter in a pressure line! Cheap skate tip two, I like to magnetize my dipsticks so they collect iron and steel particles floating in the oil and wipe them away when I check the oil. You can also collect particles by placing a powerful magnet on the side of the pan, just remove it before you take out the drain plug and they will drain out with the oil. Magnetic drain plugs, available at some auto parts suppliers also work very well. You can magnetize your dipsticks (works on screwdrivers too) with a two post soldering gun, simply pull the trigger and pass the end of the dipstick through the loop at the tip. Let go of the trigger before pulling it back out. Reverse the process if you want to demagnetize one.

Keep a close eye out for water in the housings of tractors that set out in the rain a lot as it can build up faster than you might think, especially on some models. In addition to the rusting and loss of lubrication it can freeze in the winter locking the gears and if forced can cause considerable breakage. Tractors in regular heavy farm use normally build up enough heat to stay dried out but in light use even condensation can build up to problem levels.

All of my tractors are working tractors, not show tractors and several have quite a few modifications but I always try to do "bolt-on" modifications and keep and label any removed parts. This way I can always go back to "original". This is something you might want to keep in mind even if your tractor is strictly a worker.

I will leave you with this simple thought, "oil is cheap, parts and labor are expensive".

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