1985 245
Help!
Oil resembles yellow pudding. With 305K can not afford to replace head gasket or ... Perhaps draining oil (and water) and replacing with one of the super additives? Looking for anything that will help squeezing more miles out of this otherwise great automobile. Thanks.
whooope

With 305K can not afford to replace head gasket

Why not? If the car's been well taken care of, you can easily get another 100K out of it, especially if it is as you say an "otherwise great automobile." A head gasket is cheap, and so is the elbow grease. Even if you had to pay a garage to do it, you won't be set back that much, considering how much life you probably still have left in your brick.

"With 305K can not afford to replace head gasket "
If the car is in good shape why trash it, if a head hasket set is under $60? Replacement is straightforward though time consuming.

After you've done it, you should be pleased with your decision.
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1980 245 Canadian B21A with SU carb and M46 trans

Sorry - terrible news, but with the oil as you describe (that yellow indicates a very serious leak, not something that can be fixed with a can of miracle cure), every mile you drive is bringing that engine closer to seizure (death) -- the water-contaminated oil is simply destroying the insides as it circulates. Better to change the oil and filter right now, and just let it sit until you get some cash to have the head removed (and gasket replaced), so the engine will have some hope. There is nothing else to be done. Very, very sorry.

There are no miracle cures in a can that will "fix your problem, even for a short time. The only way you are going to get any more miles out of your engine is to properly fix it.