Farm Equipment - 20-35 maintenance question

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20-35 maintenance question

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Category: Allis Chalmers
Forum Name: Farm Equipment
Forum Description: everything about Allis-Chalmers farm equipment
URL: https://www.allischalmers.com/forum/forum_posts.asp?TID=149883
Printed Date: 17 Oct 2025 at 5:50pm
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Topic: 20-35 maintenance question

Posted By: bigcountry48
Subject: 20-35 maintenance question
Date Posted: 26 Apr 2018 at 6:01pm

I’m trying to figure out what oil and how much to use for my 20-35? I checked my “owners manual” and it was about useless. Any information is greatly appreciated!

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1950 B, 1952 pulling wd, and 1954 wd45

Replies:

Posted By: Jacob (WI,ND)
Date Posted: 26 Apr 2018 at 9:45pm

I should be more help with this, but all of my 20-35's are in project state at the moment. I'm sure someone who has a running one will chime in.

As for fluid levels, that is full up to the petcocks on the engine and transmission, and governor.

Governor calls for same oil as engine.

Like you said, the period "Instruction Book No. 2017 care and operation of..." doesn't help much by today's standards of oils and greases.

I'd like to hear what other 20-35 owners are running in their tractors. Arguably, pretty much anything you put in it will be better than what was available back then.

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Jacob Swanson
1920 6-12; 1925,1926 20-35 longfenders; 1925,1926 15-25's; 1927,1929 20-35 shortfenders; C; B's; IB; WC's; WD; WD45

Posted By: Alberta Phil
Date Posted: 27 Apr 2018 at 9:59am

I've been running both of mine for years on 15-40 diesel oil from Napa and have never had any problems. I usually only run them in the summer.

Posted By: Jacob (WI,ND)
Date Posted: 27 Apr 2018 at 2:50pm

I may have asked this in the past (good memory, but it's short) but what do you run in your transmissions Phil?

Part of the deciding what to run in the tractor will come down to if this is an old engine, or all newly rebuilt and whatnot? You know, the whole non detergent vs detergent oil discussion, etc...

The '27 20-35 I'm currently working on will be all 100% rebuilt and new so when I asked the place that did my engine work what we recommended for oil, he really said it didn't much matter, any good brand of oil will work. He did recommend adding an additive to the oil for a little more lube to the valves, tappets, etc..

I may use the Brad Penn brand oil when I get that far. Supposed to be really good for older motors like this, with more additives etc. Designed for this sort of thing from what I understand. The oil is green. I have it in my 1956 Chevy Pickup I am restoring, but that project has not gotten past the getting the engine rebuilt and running phase. A lot of race car guys use it, and if it works on those abused engines it must be good stuff huh?

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Jacob Swanson
1920 6-12; 1925,1926 20-35 longfenders; 1925,1926 15-25's; 1927,1929 20-35 shortfenders; C; B's; IB; WC's; WD; WD45

Posted By: Alberta Phil
Date Posted: 27 Apr 2018 at 8:15pm

My '28 20-35 has the original non-rebuilt engine in it and I use the 15-40 Napa oil in it and have for many years. When I first got the tractor and got it running, I ran it for a while and warmed it up. Then shut it down and let the old oil drain over night. I removed the crankcase side covers and flushed the engine out with my solvent gun. After a good draining, I put in the new 15-40 and ran it for a couple of shows. Changed the oil after that and it's been fine. Wasn't much crap in the oil when I changed it so it probably would have been OK.

The '29 has a rebuilt engine so no worries on that one.

As to gear oil, I have 85-140 in them, although 80-90 would probably be OK for the limited use most of these get. I like the heavier oil especially in the '28 as that one spends quite a few hours running a threshing machine in the fall.