Correct oil for 1940 John Deere H handstart

Dwashebek · Aug 30, 2018

What kind of oil is recommended for a 1940 John Deere H handstart tractor?

Thank you,

dan_41jdh · Aug 30, 2018

When your tractor was manufactured, only straight weight oils were available, and Deere recommended "Good, clean, high-quality" oil with the oil viscosity dependent on ambient temperatures (for example, SAE 10W for below zero, SAE 50 for 95F and over). Today, because multi-viscosity oils are the standard, many people use 10W-40 which is actually better for your tractor. Detergent oil wasn't available back then, either. So if your tractor has a lot of dirt and sludge in the crankcase, detergent oils will definitely start to loosen them up and you should change oil frequently - or better yet, clean out your crankcase first.

Dwashebek · Aug 31, 2018

I've always been told that introducing detergent oils into an old engine will loosen too much "dirt or sludge" and may cause damage to the point of the motor blowing blue smoke and such after the sludge moves through the engine. Is that a correct assumption?

dan_41jdh · Aug 31, 2018

If you have an old engine that has always used non-detergent oil and has not been overhauled and thoroughly cleaned out recently, then there will be a build-up of sludge that results from a combination of oil breakdown, contaminants (dirt and water), microscopic wear particles, etc. This stuff will be loosened and can very well cause damage if a detergent oil is used. So the choices at that point appear to be to continue using non-detergent oil, use detergent oil and change your oil and filter very frequently, or best of all, overhaul the engine, clean it thoroughly, and use a modern detergent oil after that.

Dwashebek · Aug 31, 2018

Thank you!

buickanddeere · Aug 31, 2018

The cheapest Detergent oil on the shelf today is superior to the best oil on 1940z

DR. EVIL · Aug 31, 2018

If the tractor has been used regularly any time in the last 40-50 years it's been run with detergent oil in the engine.

Using a diesel rated 15W-40 with the stronger detergent package to control diesel soot in the oil is the best oil to use in these old engines.

Getting detergent oil in these old engines ASAP is the best things you can do for them. If the oil turns coal black then change it regardless of how many hours the engine has been run.

D- · Sep 1, 2018

Your filter should catch particles in sludge
dissolved by detergent oils. As others stated
you should change oil (and filter) frequently
until engine has cleaned up.
It would help if you poured in kerosene or some
other solvent to set in the bottom of the engine
a while to help loosen the sludge.

Correct oil for 1940 John Deere H handstart

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