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Engine Oil Stop Leak Additives and Low Oil Pressure

C

c-caron

New member
Bought a 1993 Sea Ray 330 with twin Merc 5.7 inboards then found port engine oil leak. The dealer had the rear main seal replaced. The problem seemed to stop. Switched to Royal Purple marine synthetic, leak started up right away. Quickly switched back to Quicksilver 25-40 blend. Still leaking. Had the same mechanic look at it. He doesn't think the rear main seal would go bad already bud doesn't know where the leak is from. Suggests pulling the engine and probably rebuild or replace since it is old.

Has anyone had luck with engine oil stop leak additives? I would rather have a clean bilge for the rest of the season than worry about the problems additives cause.

Also, I get normal oil pressure at startup but it drops at operating temp. Engine temp is normal though, and never overheats. Checked pressure with mechanical gauge. And since i have such a bad oil leak, obviously there is some oil pressure somewhere.

I'm going to switch to 20-50 conventional and run the heck out of it for a bit, see if something changes.
 
My experience when switching to synth is always the same.
Lower oil pressure when engine is warm on every engine i use it in. Normal when cold though.
Synth will create leaks where there was only a small seeping before. Synth to my understanding has smaller more perfect molecules causing this.
I do not think synth will cause a leak with a new rear main seal unless something was amiss to start with.
Maybe its leaking out of the back of a valve cover. Look at the back of the intake manifold. Check the oil pan bolts for tightness, Oil plug might not be tight, Oil Cooler.
I would look at everything else first before pulling a engine with a New rear main seal unless i was sure that was the problem.
 
You might also try a Lucas product, for that company makes excellent products that really work! The power steering pump in my PT Cruiser was leaking badly at the seal. I used Lucas power steering stop leak and it's now working fine.

Jeff
 
.."Pouring stop leak into the engine does not repair the problem. "

Thousands of motorists out there will disagree with you!

Jeff
 
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