What Oil for T’s


By E. Meloan

(This article was originally published in the September, 2002 issue of the Spark Coil.)

Hi fellow Model T’ers!  A question came through the E-Mail Model T a few weeks ago that made me realize that some of the things we “old timers” take for granted may not be known to new folks who are just getting their first Model T.  With that in mind, I thought we might discuss some things that might be helpful to a new owner.

Let’s begin with one of the most common questions asked by new owners. “What oil should I use?”  Ask a group of T owners that and your probably get at least three or four answers…  ALL different!  Some owners will suggest that you use a non-detergent single weight oil.  Probably 30 weight if the engine is in good shape and 40 weight for an older loose engine.  While there is nothing in this advice that will do any harm, I don’t believe it is the best oil for our T’s.

Modern multi-viscosity oils with detergents might almost have been made with the Model T in mind!  They keep the dirt in suspension rather than letting it coat the insides of the engine provided we do our part and change the oil reasonably often.  They control foaming and the T engine surely needs that with those sixteen magnets churning up the oil!  They don’t thicken in cold weather, making the car much easier to start.  And, they maintain their viscosity and lubricating qualities when the engine gets hot during the summer.  Pretty good reasons to use them!

The one place where a non-detergent single viscosity oil might be good would be in a newly rebuilt engine for the first 500 to 1000 miles.  The superior lubricating qualities of the multi-viscosity oils probably prevent the small amount of wear we want so that rings will seal and parts will wear in and seat themselves.  After 1000 miles with non-detergent, I’d switch to the multi-viscosity detergent oil.

There has been considerable discussion about whether it’s ok to use a detergent oil in an old engine that has built up a lot of varnish and deposits over the years.  Some folks feared that switching to a detergent oil would cause these deposits to loosen and clog the small oil holes in the bearings.

The research departments of a number of major oil companies have tested detergent oils in heavily coated old engines and found that rapid loosening of the deposits does not occur.  Instead, a gradual washing away of the deposits takes place over a period of time with the engine becoming cleaner and cleaner.  This does suggest that if we begin using detergent oil in an old, dirty engine, it might be a good idea to change the oil much more frequently the first few times.  Maybe after the first 100 miles and then every couple hundred miles up to the first 1000.

Multi-viscosity oil can really make a difference when starting your Model T!  You’ll be pleasantly surprised at how much easer the engine will turn over with a good multi-weight oil.  This is certainly true in winter but can even be felt in summer as well.

So… what weight oil is best.  A number of weights have been recommended in various discussion groups but I have found plain 10w30 to work as well as any.  It’s easy to find and relatively inexpensive.  If I had a worn engine, I might move up to the slightly thicker 10w40 to add a little more cushion and help the leakage somewhat.

The oil troughs under the rods catch a fair amount of oil and, when we are changing it, these troughs keep a lot of dirty oil in the crankcase which immediately mixes with the fresh new oil.  There’s an old saying amongst the old-timers… “A half gallon of clean oil added to a half gallon of dirty oil makes a gallon of dirty oil!”  One way to get some of this dirty oil out is to jack up the front of the car as high as you can, leave the drain plug out, and pour a quart of clean oil in the engine.  You’ll be surprised at the additional dirty oil you’ll see coming out the drain!  Put in the drain cap, let the car down and add your new oil. I’ve found that it takes about 3 and a half quarts when the troughs are already full.  It’s not a bad idea to add the other half quart as oil helps cool the engine.  The down side of too much oil is that the T engine will tend to smoke more if not in good mechanical condition.

When checking oil, open the top petcock.  If you have flow there, you have more oil then you need.  If no flow, open the bottom petcock.  If no flow there, you better be opening a few cans post haste!  Be sure it is a stream and not just a drop or two.  You can get a drop even when the oil is below the petcock!

We’ll continue these tips for new T owners and drivers in our next issue.  Until then,

I’ll see you down the road…