Thoughts on "Motor Flush" with additive to oil ???

[NASCAR314]

Just curious as to anyones thoughts or experinces with flushing out a higher mileage older motor using an additive such as "Gunk" or plain old kerosine, or whatever else. I seem to have a sticky lifter or two and the motor was neglected by the previous owners. It's a 73 BBC in question, actual mileage unknown. I have replaced the pan gasket and everything looked good, but there was a lot of black crap stuck in corners and in non-moving parts area's. Very little if any oil burning past pistons. Runs strong otherwise. Looking for comments on Motor Flush additives mostly, YES, or NO WAY! Thanks, Tom

[427Hotrod]

My experience has been that if the engine is funky inside, it is best to leave it that way until you rebuild it. This assumes there is enough oil drainback to not be causing issues there.

I've seen several cases where flushes were run through. They do clean stuff well, but they can't get everything and inevitably stuff ends up where it ain't supposed to be. Or the bearings get scuffed up. They usually fail soon after. All that crud is sealing leaks etc. Once washed away it will leak and most likely start using oil etc.

Same way with radiator flushes. Almost guaranteed you will be replacing freeze plugs, water pump or heater core not long after using it.

Either maintain it all along, or leave well enough alone until you can start over.

You might try a qt or two of auto trans fluid. It cleans very well and might free up that lifter. But don't run it too long. 50-100 miles max. Get it up to temperature, light loads.

Just my .02


JIM

[NASCAR314]

Thanks 427Hotrod,
I've heard that the automatic trans fluid is a great detergent additive, Locally I've been told to run 1qt. for about 50 miles and drain it hot! Then change oil & filter regularly at close intervals a few times till clean.

This motor is not too "funky", I've taken some funky motors apart and could not belive that they even ran at all!

I'm dealing with light buildup probably from poor maintenance from previous owners, or lots of short trips.

Thanks,

[71coupe]

The best way to flush a motor is to by a cheap case of no name motor oil & a few cheap filters. Change the oil like you normaly would, drive it for 30 minutes then do it again. Keep doing it until it comes out clean. I would use this method on cars that had lots of sludge. I think it's the safest way to purge out the motor.

[Vetterodder]

I gotta agree with the "if it ain't broke, don't fix it" logic but I'd also be inclined to follow 71 Coupe's advice. Instead of using "cheap" oil and filters though, I'd stick to good quality stuff and spread the intervals out much more. One of the biggest differences between cheap oil and quality oil is the detergent package. If the goal is cleaning the engine, you'll want good detergents and to leave them in the engine long enough to do their job. Check the oil frequently and when it starts to darken, change it. It may only take a few hundred miles before the first oil change and then will probably take longer before the next one is needed and so on. Eventually, most of the crud that's going to be removed will be and without having caused any dangerous clumps being released.

[mountainmotor]

The use of ATF is a old Wives tale. It does not have near the detergent/didpersent pckage of a motor oil. Here is a anaylisis of Dexron III. The values are in parts per million,calcium is the detergent. A HD oil will have around 3300 PPM of Ca.

Additives
Molybdenum 0
Sodium 6
Magnesium 1
Zinc 3
Potassium 0
Phosphorus 255
Calcium 224

Typically oil alone does not clean an engine it helps keep a good one clean though. You might try a HD Fleet oil like Chevron Delo,Phillips HD ect for a couple of changes,,it will clean it a little and do it safely with it's robust additive package.
Here is a analysis of Rislone:

Molybdenum 0
Sodium 0
Magnesium 0
Zinc 380
Potassium 0
Phosphorus 352
Calcium 768

And here is a Virgin analysis of Conoco HD Fleet Supreme 10/30 motor oil

Phosphorus 2217
Zinc 1893
Magnesium 467
Calcium 4517
Silicon 5

Using a Polyolester basestock oil for one interval will help also,this can be found in Redline brand and a handfull of other exotics

Hope this helps

[Modified by mountainmotor, 7:03 AM 4/22/2003]


[Modified by mountainmotor, 7:08 AM 4/22/2003]

[Matt Gruber]

i scraped out 3 pounds of sludge from the pan and valve covers on my 67 289. it had chunks of rock hard sludge break off and clog the screen which sucked in a piece of valve seal and locked up the oil pump and broke the shaft.
just thought i'd add this tidbit from the trenches :smash: (other than hand scraping, or a hot tank or acid dip, i don't think any flush will clean even what is left in my 289, which now runs fine with a new pump/shaft.