Tue 18 Nov 2008
Posted by mark under Model A Ford
Comments Off on Which Oil To Use In A Model A Ford
This weekend the 3-River Region Model A Ford Restorers Club had a garage seminar about motor oil. It was great.
The question of which oil to use in my Model A was a difficult one for me from the beginning. It seemed like there was a lot of conflicting information out there, and I didn’t know what to believe. This may not be the final word on the subject, but I feel like I now have the answers.
Our guest speaker for the seminar was Ken Pyle from PPC Lubricants. He gave us some history on oil in general (I didn’t know that oil native to the Pennsylvania area was the best natural lubricant, and that crude oil from different regions was not all the same), and then we got into the info that we really needed for our cars.
Older engines are just different than modern engines, so their oil needs are a little different too. Older engines (pre 1990s) need oil with higher levels of zinc and phosphorus to act as anti-wear agents that newer cars don’t want, since too much of those additives will mess with modern catalytic converters and emission systems. Also, modern engines have tighter tolerances, so they are now using oils that are too thin for old cars. Interestingly, we can also use some diesel oils because Diesel engines have the same additive needs as our Model A engines.
Oils that have been tested by the American Petroleum Institute (API) have a rating “donut” on the back of the bottle. You can read the codes in the donut to see if the oil is what you want. The photo below has a donut that reads “API Service SM”, which is higher than the preferred maximum rating of SJ that we want for the Model A. We can also use some diesel oils because Diesel engines have the same additive needs as our Model A engines.
Ken’s Top recommendation for the Model A is Brad Penn SAE 40 Racing Oil. It does not have the rating donut on it, but it does have everything we need in an oil.
One advantage that is particular to this oil, is that since it is made from 100% Pennsylvania Grade oil it has unusually good stickiness. 80% of engine wear comes from dry starts, so you really want that extra stickiness to keep the oil on the parts where it belongs. The only problem is that Brad Penn is a regional product, so if you can’t find it, here are the guidelines for selecting the right oil:
What you want:
– Straight 40 weight oil (SAE 40)
– Rated no higher than SJ (SC is lower, SM is higher)
– Detergent Oil (to get rid of sludge)
– Diesel Oils rated no higher than CI-4 (CJ-4 is higher)
– ZDDP additive (zinc & phosphorous for anti-wear, oils rated higher than SJ or CI-4 do not have enough ZDDP)
What you DON’T want:
– oil without an API rating donut (like from the dollar store), unless it has all the properties in the above Want List
– SA or SB rated oil
– Diesel Oil rated CJ-4 and higher
I am not an authority on this subject, and all of this information is new to me, but I think this gives us a pretty good idea of what we need for the Model A Ford.