Seafoam

It can be used as a gas additive which sends it through the fuel injectors. This will be diluted with gas in the tank and provide a slow cleaning of the entire fuel system. Adding it through the brake booster vacuum line sends it directly into the cylinders through the intake valves. This will cause the white smoke and clean varnish/carbon on the top end. The biggest danger in doing it incorrectly and pouring sea foam (an uncompressible liquid) directly into the cylinders. This can destroy your engine if you try to start it with built up fluid an the cylinders. I have personally seen this happen. The block was cracked as a result. Adding it to the oil will clean the bottom end to flush varnish deposits that build up there. I agree that the longer you wait in adding it to your oil, the more chance of something going wrong in the bottom end of your engine.

 

people say no crank case for high miles...

i have an 01 with nearly 130k is that high? (seems high but compared to the 200/300k its nothing!)

 

What I'm going to tell you concerns engine flush, which of all the brands I've sold over the years, they all boil down to basically kerosene. Seafoam is a different animal altogether, but to an extent it will affect a high-mileage engine like regular engine flush will. The issues concerned relate to bearing looseness and other slack in an oil system that's seen a lot of miles.

If you're going to do a high concentration dosage of Seafoam, more or less flushing the motor, let the engine warm so that it will run at low idle BEFORE putting the stuff in. It works by removing deposits, but it also removes the oil to an extent, from the bearings. At warm, low rpms, you'll not have enough pressure from the combustion cycle on the bearings to prevent what oil's there from lubing them. Do NOT rev the engine though, or you will overcome the lubrication of the residual oil.

After ten minutes, drain, change filter, and refill. You're done.
Where there's a conflict in my advice is that when an engine's cold, the oil is thicker, so since the Seafoam/flush will thin the oil out, it seems like this would be the best time to run it, not when the engine's hot.
The drawback is that a cold engine is going to idle up so much that I'd not trust being able to keep enough chemically thinned out oil in the old loose bearings.

I figure since the oil's going to be thin from the Seafoam/flush either way, I'll play it safe and use it in a warmer, low idle engine.

IMO, if I were going to run Seafoam in there all the time, I'd either use a lesser dose in a high mile engine than what the product recommends, or I'd just run some transmission fluid in the oil all the time. It's such a high detergent, you'll get a lot of the same cleaning.

My 2 cents! With all that said...all you can do is use your best judgment on the condition of your motor.

 

Just buy good gasoline and change your oil as directed in the owners manual and save your money on additives, I would never flush an engine,and chance rod and main brg damage!

 

Be carefull. Dont put it in a hot engine. The cold seafoam dumped into a hot engine could cause issues. Prolly wouldnt, but why even chance it.