I am currently having some work done on my '30 Model A that I am physically unable do at this time. I had the guy look at inside of the engine, he said it looks good but there was a lot of sludge from the previous owner letting it sit for long periods of time. The engine is the original four cylinder flat head; about 95,000 original miles. What would be the best oil to use? Synthetic or not? What weight? And should I use an additive to break up the sludge?
Model A books call for 60 weight oil, I run Havoline 60 w racing oil in the two I have. They are usually full of sludge, no filter and low operating temperatures cause sludge. They have a clean out plate under the oil pump in the oil pan to help get rid of sludge. Any good grade of oil will work, I know people who run modern detergent multi weight oil with no problems. Model A's aren't really a pressure system, the oil pump pumps the oil up into the lifters and it gravity feeds the main bearings from there. The rods are splash fed from the tray under the crank, as they turn they pick up oil out of the tray with dippers on the rod caps. Very basic oiling system, doesn't require much just a good grade of oil and frequent changes.
Well I went to the garage and dug out a couple of books and looked online and found recommendations for 30 and 40 weight oils so I stand corrected. I also looked at a spare quart of oil I had and it is 50 weight rather than 60, it's tough to get old and forgetful.
15 40 diesel oil. made for flat tappet motors, most still have zinc. cheap stuff, change often to get rid of the non detergent crap
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