ENGINE FLUSH?

[cab83_750]

OK,

For the last 2 decades, I have been flushing the engines every other time I change the oil. Just for clarification, flushing is the addition of a can of 'kerosene smelling' liquid in a silver can, letting the car idle for 5 minutes, and then changing the oil.

Flushing may be a great idea for non-P cars. But with the 911 having the oil lines, the oil cooler, etc., wouldn't adding this gunk stay in the oil lines and ESPECIALLY A BIG CHUNK IN THE OIL COOLER? Would this damage the 'oil viscocity'?

I have not flushed the 911, and I am wondering if I should.

[jsmarcus]

I flush once a year. Last time I did, though, I forgot to use the larger drain pan and ended up with a floor full of oil. Make sure you have a HUGE oil pan to catch all 13 quarts in there. I think the car runs better after a flush, and definately burns less oil.

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Josh
Black on Black '84 Carrera

[cab83_750]

Marcus,

Thanks for the input!

How do you make sure you do not have old and tainted oil in your oil cooler and oil lines? I think the flush is 'kerosene-based' and I recall when I was a kid that rubber disintegrate in kerosene. This is the reason why I am concerned about leftover inside the system.

Do you just ignore this possibility or fact of old/tainted oil staying in the cooler? As for the container, I do have a super big container so this is not an issue.

I am tempted to drain the oil and once 'dry', I would run the engine to very momentarily (repeatedly) to "FORCE" old oil out of the cooler and lines.

Input??????????

[makaio]

I by no means am a Porsche expert like John Walker, Warren, or Roland, but I would not run the car with no oil! Bad things could happen.

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Matt Chamblin
78 911 SC

[kiwior]

Running the engine dry will not force anything out of the cooler since there would be no oil at the oil pump and thus no oil pressure. This would only cause damage to your engine. There is also an oil thermostat isolating the cooler from the rest of the system.

[emcon5]

To keep the flush stuff out of the oil cooler, run it through when the engine is cold. As long as you stop before it gets hot enough to open the thermostat to the front cooler.

Tom

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82 911SC Coupe

[Ted Stringer]

Use good oil and you should not have to flush the oil system at all. If the stuff that you describe is kerosene based that it will do a lot of harm to the gaskets in the engine. Also it will not do the bearings in the engine any favor because kerosene is much closer to gasoline that engine oil. My advice is to never put anything but oil into the oil tank.

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Ted Stringer
nuke3@juno.com
'84 911 Targa aka pocketrocket

[cab83_750]

Full synthetic oil all the way since day one! So this is a none issue.

I like the idea of running the gunk BEFORE the thermo opens.

[Clark Griswald]

I'm not so sure the thermostat idea will work. Some oil thermostats allow 10% of the oil to flow through the cooler even before the oil reaches temperature, then 10% to bypass the cooler after reaching temperature.

This is to avoid a thermal "shock" when the thermostat opens, and a complete loss of oil pressure in the event of a clogged cooler.

I am not sure if the 911 factory thermostat has this feature.

You could disconnect the oil lines and drain the cooler.
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Chuck Moreland '86 Cab - "Sparky", '77 Targa - "Sweet Pea"

[Planter91C2]

if you have been using fully synthetic oil since day one and heve kept up with your oil changes i think it is silly to do a flush. the risks far outweigh the rewards. i would be interested by what others think, but i wouldn't do it.


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Daryl 964 Targa

[pbs911]

Running Techron in the fuel before an oil change does two things. It cleans the fuels lines. It also works its way into the oil. Hence, the need to change the oil after treating the fuel system with Techron. It seems to me that maybe the reside Techron that is deposited in the oil may act like an engine flush, well sort of.

Never run a motor without oil!!! Even for a short period of time. Even on a brand new motor, if you didn't apply lube to the bearings and such you can cause significant damage upon the initial start up of the motor.


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Paul
78SC Targa

[FrdzRed]

I believe that most oils already have a detergent additive in them so I wouldn't think that flushing an engine would really buy you much. Besides that I'd think that any residual "cleaner" that was used would only thin out the new oil.

[Jim T]

Originally posted by Ted Stringer:
My advice is to never put anything but oil into the oil tank.

I think that is the best advice in this thread.