Are any of these oil additives good to use on a 25 year old engine? There seems to be a few to choose from. Marvel Mystery Oil? STP? Etc.

First, we need to know what you are trying to accomplish with the additive. Correcting a problem, wear reduction, quieting an noise, smoking, oil comsumption, mileage improvement?

Some additives work well for some purposes, but can be counter productive for others. Some are universally good, but may not do what you want. Some are universally snake oil, and a waste of time, money, and can actually hurt your engine.

What do you have, and what are you shooting for?

|UPDATED|5/16/2004 8:50:47 PM (AZT)|/UPDATED|

I agree with Ken. You have to know what you're trying to accomplish. There are specific treatments for specific problems. I do believe most additives do little or nothing to help.

That being said, and the fact that I remember the early '60s, one additive I always have used and continue to use is the old standby Scientifically Treated Petroleum, or STP (or STudebakerPackard, who used to own STP and the Granatelli Brothers). A longtime acquaintance who built engines always coated the internals with it when assembling a motor and I trusted his judgement. I've never had a problem, though I do tend to overmaintain cars anyway. My Dad always swore by Marvel Mystery Oil which is still widely available.

About the only other additives I will normally use is a good quality water remover for the fuel and fuel stabilizer for winter storage of the car. Outside of that, I don't use additives unless I have a specific issue to address.

Check out this forum for oil and gas related issues!
http://theoildrop.server101.com/cgi/ultimatebb.cgi?

Thanks for the advice and link. I had noise (lifter?) at startup after sitting for a week but would go away after she was warmed up. When run more regularly I would not hear it.

I put in Marvel Mystey Oil (something about that name bothers me) by the directions. The noise went away and has not returned. I understand that this product cleans things up a bit and I should change the oil after a couple hundred miles. I have had only short runs since then but plan to change soon anyway.

O.T. My daily driver 02 Tahoe V8 (36,000 miles) also makes some tapping kind of noises now at startup everyday. Should I use some kind of oil treatment for that?

well since you both of your vehicles are doing the same thing.. i would look at the oil you are using.. may be its time for something thicker.

what kind of oil are you using now ?

|UPDATED|6/6/2004 4:23:31 PM (AZT)|/UPDATED|

For the vette, Valvoline Max Life 10W30; Tahoe, Castrol 10W30 or Valvoline regular 10W30.

In addition to other toys, I have a 1989 GMC truck with 220,000 miles on the original mill. I use Castrol 20W50 in Summer and Fall and 10W30 for Winter and Spring. No knocks, knicks, clicks, clacks or rattles.

Not a universal solution, but it works for my stuff in the Mississippi heat.

John

PS - The difference between Summer and Fall in Mississippi? About 2 degrees - from 106 all the way down to a right chilly 104!

lumberjack said: In addition to other toys, I have a 1989 GMC truck with 220,000 miles on the original mill. I use Castrol 20W50 in Summer and Fall and 10W30 for Winter and Spring. No knocks, knicks, clicks, clacks or rattles.

I agree you need to use something thicker in the summer at least ... 20W50 should be fine for florida (in the southern half at least) all year round