Oil - old tractor and old cars

Saw another discussion up on the antique car club forum I frequent that got me thinking about my newly acquired SC.

Both of my Studebakers have solid lifters and a decade ago many club members started recommending diesel grade oils because many regular gasoline grade oils were moving away from the additives needed to help preserve those solid lifter engines.

A few years ago, diesel oils started moving on to a newer rating (CJ - low sulfur or something like that) that cut down on those helpful additives. Now many older car owners are having to add ZDDP to the sump with each oil change to try and keep everything under the valve covers happy.

I guess I am wondering if I need to watch what kind of oil I put into my C123 (went with TSC's 15W40 diesel grade the first refill a few weeks back) or am I being an over-protective owner?

My uncle used to tell me that back in the day (40s & 50s) he never changed the oil in any of his tractors. He said they usually leaked enough that they would need a quart every week or so and with a filter change every three months you were in good shape...never had any breakdowns because of oil problems...

Thanks ahead.

Anything you put in it is better than the oils that were available when the tractor was new. I use 15W40. In year round warm climates SAE 30 is fine, some use 10W30, probably ok, but in my opinion the tolerances in 50-70 year old engines are too large for that one. The only oil that is "wrong" is nondetergent.

The ZDDP levels were brought down by Big Brother as it tends to foul the cat converters on new cars, and the manus were required to make the cats last longer. The new cars all have roller lifters or followers and can get by with the reduced ZDDP. Anything older with a flat-tappet setup needs a little help, the sliding-friction being where the ZDDP is needed. An easy solution is to use off-road oil like Brad Penn, available at most speed shops, Valvoline VR-1 from Kragen etc., and some of the Mobil1 stuff still has good levels of ZDDP. Considering that most of these old tractors are more toys/pets these days and don't rack up that many hours, no reason to not go with the right oil and protect them, just doesn't cost that much more

Some people live to find things to complain about that "aren't as good as they used to be". Zinc levels gives them something to complain about. For a few others, it gives them another way to separate people from their money.

Yes, first it was unleaded gas. That didn't get anywhere, so now its Znless oil. Theoretically both make sense. On a practical basis probably not.

(quoted from post at 11:27:54 09/05/10) Yes, first it was unleaded gas. That didn't get anywhere, so now its Znless oil. Theoretically both make sense. On a practical basis probably not.

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Before that, it was detergent oil. Back when most of these tractors were designed and built, there wasn't any lead in the gas or zinc in the oil.

TEL (tetra-ethyl lead) was first commercially used in gasoline in 1924. Any dual-fuel tractor does NOT need, and did NOT need lead. Kerosene never had it. in fact, I would go as far to say that the gasoline only tractors up through the 1950's (early) will run just fine on regular or mid-grade (87 or 89).

When your compression ratio starts getting around 7:1 or greater, then higher octane is an absolute requirement. BUT, it still does not have to be TEL. Your SC should be around 5.5:1 or there abouts. Regular gas will work just fine.

As far as the oil goes, clean oil, and regular oil changes as required is all you need.

any of the F-series or Letter series tractors are low compression, low RPM's. Clean oil and clean fuel is what they crave.

As CNKS pointed out, any modern oil is going to be better than what was in there in the 50's. The quality of oil has been continuously improved by technology.

That being said, the newer CJ-4 stuff is engineered to be backward compatible. ZDDP is old tech stuff and newer tech stuff is replacing it.

Another thing to consider when you look inside these older tractor engines is that there is a lot of bearing surface area for the loads and power levels. Also the valve springs loads are relatively light in keeping with the low rpm's these engines run. They would probably do fine with just about any modern oil, although I wouldn't go lighter than a 30 straight weight or 15w-40 myself.

It's more important to keep clean oil in it than to have fancy oil. The racing type oils have higher zddp levels, but lack the quantity of detergents needed for street driving and tractor use. They know racing engines don't put very many hours on an oil charge.

A quick check of several Nebraska tests of letter series tractors (up to about 1951) showed the gas used in the tests was in the range of 70 to 74 (motor method, add about five to match the pump labels).

Gas in that octane range probably had little to nothing added to improve octane rating.

The compression ratio of my 460 is 7.2:1. Operators manual says to use a minumum of 87 octane, research method, or approximately 80 octane motor method. Using the current rating of R+M/2 makes the recommended octane rating 83.5. Regular unleaded in my area is 87. Been my opinion ever since leaded was phased out in the early 70's that a little less than 9.0:1, maybe 8.5 or so meant higher octane. Being conservative I would think that my tractor would do fine on 87, if the compression ratio exceeded 8 then maybe higher octane should be considered, particularly if carbon buildup is a problem. This octane thing will probably be argued forever.

I would not worry about
CJ-4/SM in you 123 .
For the Studebaker I would stay with CI-4/SL.
You can still find this oil . Farm stores and bike shops. If your are adding ZDDP know what you are doing. Too much is not good either from what I read.

Any good modern quality brand straight 30 weight or 15-40 weight should be OK in my opinion. I would definitely not go lower than 15-40 in a multi grade oil as in multi grade oils, the base oil is actually the lower viscosity, in this case 15 weight oil, with additives added to make it act like 40 weight when it gets hot.

Harold H

Actually elevated ZDDP is only needed during breakin of a high loading cam. Once breakin is over the need for ZDDP is greatly reduced - even in a high lift, long duration profile cam (unless its something pretty extreme), something you'll not see in a tractor engine or stock (or even most modified) Sudebaker engine.

I have a feeling there are more cases of lousy mechanics blaming the oil and gas for their mistakes than cases of "bad oil" or "cheap gas" ruining an overhaul.