Rod Knock Oil Additives?

My friends motor has developed a pretty bad knock above 3k, and the decision has been made to just drive it into the ground.

Is there anything that can be added to the oil that will help extend the life of the motor before a rod is thrown? Or are additives really just modern snake oil?

Spin on a new filter and dump in 2, maybe 3 bottle of STP oil treatment. That might get you a couple hundred miles out of it.

Top up crankcase with 90 wt gear lube. Use the money you would have wasted on snake oils to buy this lubricant for the owner.

90wt gear lube is only as thick as 20w50 motor oil and will attack whats left of the bearings. Agreed on the Jim Beam though.

Saw dust yo.

thickest engine oil you can, keep it under 3k. i put a 249k mile engine into my car knowing it was knocking, because i needed it driving NOW. i ran thick oil and put 5k more miles on it before i finally pulled it out for the engine i was putting together. it never did let go.

I drove a badly knocking 948cc Bugeye Sprite DD/autocrosser/mountain road burner for months by adding more and more STP. I also had a 2nd generation Datsun P/U that went through the same torture. It makes you grit your teeth but one does what one must. At least I didn't destroy either engine.

Edit: I just remembered a technique you can use in driving a knocking engine. Keep the engine slightly lugging or decelerating all the time. I think it helps keep the bearing in at least slight contact with the crankshaft throughout the stroke. With some practice you can keep it fairly quiet and therefore prolong it's misery.

It is a easy job to change out rod bearings (if it is the big end). Why not just change them?

wvumtnbkr wrote: It is a easy job to change out rod bearings (if it is the big end). Why not just change them?

I moved across the country about 1.5 years ago, and now live in an apartment and didn't bring any of my tools!

I had an old Capri with a 2.0L with a what I later found out was a spun rod bearing. At the time I purchased the car it was just a very mild knock at higher rpm. I added 30W oil and drove the car right through a Midwest winter. Keeping the revs down is a key. I short shifted that Mother. By spring the thing would start knocking as low a 2K rpms. At that point I pulled the engine and fixed it.

wvumtnbkr wrote: It is a easy job to change out rod bearings (if it is the big end). Why not just change them?

Doesn't fix it all the time.....a loud knock normally either flat spots the crank or rod. Or at least it did on the ecotec I replaced rod bearings on. With the amount of aluminum in that ones pan, I'd hate to see its head.

Try "Engine Restore" snake oil. You'll be out $10.

Gear oil has bad things in it for plain bearings. Stick with 20/50 and Lucus additive.

Use whatever the guy put in the AE92 GTS I bought a few yrs ago,certified it and changed the oil etc and in less than a tank of fuel the oil pressure was nil at idle and knocking.Less than awesome.

Amsoil has an SAE 60 motorcycle oil. thickest I've found.

kevlarcorolla wrote: Use whatever the guy put in the AE92 GTS I bought a few yrs ago,certified it and changed the oil etc and in less than a tank of fuel the oil pressure was nil at idle and knocking.Less than awesome.

Same thing happened to me with a chevy 4.3. Still drove it for awhile after that but it was annoying.

I think Harley-davidson sells some thick 60 or 70wt oils.

Every bottle of STP in ~5 qts of oil gets you about 10 points.

The best mix I have found is 50/50 gear lube and ATF, I know kind of weird but I got another 5K miles out of the car.

Paul B

EvanB wrote:

kevlarcorolla wrote: Use whatever the guy put in the AE92 GTS I bought a few yrs ago,certified it and changed the oil etc and in less than a tank of fuel the oil pressure was nil at idle and knocking.Less than awesome.

Same thing happened to me with a chevy 4.3. Still drove it for awhile after that but it was annoying.

Girl at work has an S10 with a 4.3 that knocks like a mother. She's driven it a couple thousand miles like that. She said she used "motokote" to minimize the noise. Whatever.