If the oil looks fairly clean and not grease like, drain it and add new oil of your choice, 10-30 or straight 30 weight and run it. Removing the valve cover and oiling the rockers would be good advice before starting and leave it off once it starts to check for oil pressure. These are low pressure engines compared to modern ones so it shouldn't spray everywhere. This engine has no oil filter unless it has one mounted by a dealer or previous owner. If it does have one its not a 100 percent filter, meaning only a small percent of the oil gets filtered at one time. Over time all the oil gets filtered but it takes quite a while.
You might need to change oil a few times till it cleans up. If the oil looks like sludge, fill the engine with diesel fuel if you can afford it, and let it set for a week or so. Then drain and fill with oil of your choice. Running clean oil and one quart of dexron trans fluid will clean them out as well, trans fluid is high in detergents.
Be aware you can break loose a lot of dried bits of stuff in the engine and can plug up the pick up tube. If theres any doubt about the condition of the engine, pull the pan and clean it along with the pick up tube to the oil pump. To check for sludge, poke a stiff wire in the drain plug hole and dig around on the bottom of the pan to see what you find. Then you will know if you have to pull it or not.
Todays oils are much better then the old stuff so your choice of what to use really comes down to what brand you like. Theres really no need for additives (zinc) since this is a stock, well broke-in engine.
Joe
Last edited by Joe H; 03/07/2011 3:50 AM.
