So the consensus would be to run all the AD,CD,JW and all motors with the plain bearings on 16:1 TCW-3 oils? What about synthetic and synthetic blend oils? I know Tubs uses synthetic oil at a little lighter ratio and seems to have good luck. Is synthetic oil a much better lubricant than TCW-3? Even the Merc KE4 calls for 16:1 I believe and they’re supposed to be roller bearing motors I thought. I have a 1975 Evinrude 6HP and now I realize it has plain bearing wrist pin bearings( never really thought about it before) and it too should be run on a heavier oil mix.
Your 70s model 6hp will do OK on the 50:1 mix. Using a little extra oil on your 6hp wont hurt a thing, and the thermostatically controlled cooling system will help reduce any possible smoking. True, the wrist pin uses a plain bearing, but the bid end of the rods use needle bearings. I have never seen an wrist pin issue on a 6hp. The older 10hp models are a different story indeed.
Again, no one will dispute that oils have improved greatly over the years. And, there may be instances that the oil mix can be lightened up a bit. But, I sure won’t attempt to address that here. In the end, it is up to the owner. But, I would never attempt to run any of my 50s model plain rod bearing (big end) engines on anything less than 16:1. These engines smoke very little, even on the heavy 16:1 mix, when in good tune. Rod failure is not uncommon on these engines, and a little extra oil is cheap insurance indeed.
The engines we are referring to are older models with plain bearings on the big end to the rod/crank. I guess I should have been more specific in my descriptions, sorry. D
