Engine Flushing

I haven't seen anyone offer this sort of flush service. It would be easy enough to do, technically.

Whether it offers any advantage over frequent oil change is questionable.

I have flushed engines that got full of water due to gasket failure, cracks. I used Stoddard solvent, which does not affect seals to any great extent, followed by isopropanol. Then several oil changes at short intervals.

Hope I'm not sticking my nose in here; I did not get the whole story here. As far as an oil flush, etc. what I did was use 4 quarts of

10x40 and one quart of kerosine. I let the engine run for about 10 minutes and drained. I did this twice. The final drain was a regular oil change and filter. This seemed to clean out much accumulated junk.

Hank from PA

From the bobistheoilguy.com forum, AutoRX

isa very safe way to do it.

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Just run either a synthetic oil or else a Diesel rated oil like Shell Rotella, change oil and filter at short intervals and make sure engine is running at full temp. This will clean out crud slowly and safely. Only if it's REALLY gunked up should you need to resort to more drastic measures. I'm running Rotella in my old Studebaker which had a really dirty engine when I got it; after maybe 500 miles the filter element weighed more than twice the new one I replaced it with. Best thing is it's cheaper than regular Valvoline etc. and still carries current API ratings for gasoline engines.

nate

Hank wrote:

Why do you want to flush the engine? Before you do that, take the oil pan off and see what's there. Chances are it will come pretty clean.

If you are using a good quality detergent oil, there should be no sludge build-up with regular oil changes. The key is detergent.

Doing a motor flush does clean out all the old oil but you know what? You need that remnant oil film to lube the engine while the new stuff is pumped into place when you start the engine after the oil change.

I would flush mine if varnish is involved. I noticed this recently, and used additives, changed oil brands.

Everytime you change your oil, you could argue that the oil film has been depleted. If you really worry about it, prelube or disable the ignition (maybe fuel pump is easier nowadays) and turn over the engine a few times after you add the new oil. Since you don't start the engine, extreme pressures are not encountered and damage is minimal.

If you have some substantiable data on damage from flush operations, I would like to see them. Heck, I can't even find reliable data on the effect of fines on abrasion in the oil. Lots of claims, no data yet.

You'd have to do that on every start, then.

My point, exactly. If you let the car stand for a few weeks while you are on vacation, for example, it will be dry. You could go through this rigamarole but nobody does it.

In fact, oil supply normally pressures up fast enough that no significant damage is done.

Unless it's 5 degrees below zero, the choke sticks and redlines the motor, and your wife doesn't think to turn off the key in your '84 Cutlass that you loved dearly...*sniff*.

Touche'...

Not so much that pressures build fast, but oil film is a LOT more persistent than you'd think. I've cracked open junkyard engines that had been sitting in the weather for years, and still had a good thick film of oil on things like the bearing journals where the oil film is sealed between the crank bearing and the bearing shell. The cam and cylinder walls can dry out faster, but even there you typically find a little bead of oil hanging to the bottom of every cam lobe after months or years of sitting. The real risk area is the cylinder wall in the space ABOVE wherever each piston comes to rest when the engine is shut down, and even pre-lubing doesn't help that. Which is why its good to run a stored engine periodically, or else fill the cylinders with light oil through the spark plug holes if you are planning to store an engine for a very long time.

I don't drive much in winter so before I start the car I use the starting motor to turn the engine over a few times to "lubricate the cylinder walls". Is that a usefull thing to do?

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I guess that depends on the engine. Most engines use oil pressure to squirt oil up onto the cylinder walls, but I'm not sure cranking with the starter motor really builds enough pressure to spray the oil up there in most cases. Other engines rely on the cranshaft to fling oil up on the cylinder walls, and in that case I'm pretty certain the starter doesn't turn the engine nearly fast enough to put any oil up there.

I used a simple engine oil flush, pour it in, run engine for 10 to 15 minutes, then drain. I have always used regular oil in my car engine but last month I decided to try synthetic oil to see just how good this oil really is. I drive alot and change the oil in my car every month. I did a flush of the old engine oil and installed a new oil filter, then filled it up with 4 litres of synthentic oil at a cost of around $25 for the 4 litres of oil. I drove hard for a month and this is what I found. It had no noticable performance enhancment that I could notice, although it seemed to start easier in the really cold weather. One thing that I was really impressed with was the durabilty of the synthetic oil. There was no noticable varnishing or sludge buildup in the engine and the color of the oil was still clear after one month of hard driving. With regular oil in my car after the same period it would varnish the dip stick, build up sludge under the oil cap, and turned dark dark brown almost black. The durability of synthetic oil was impressive in my opinion. If it wasnt so expensive I would use it all the time, it's clearly better then regular oil IMO, but for the cost.