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Discussion Starter #1
My '78 sud 1.3 super is using a lot of oil, can't remember how much exactly as its been off the road for the winter, but more than seems reasonable. The exhaust is dirty grey, though not black, and is particularly so when the engine is cold, clearing a bit as it warms. There are no external oil leaks so I'm guessing something is worn in the engine, though it runs a treat otherwise. Does anyone have any suggestions of where to start looking? Thanks for any help!
 

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The colours I can think of are:
White: Water in the exhaust.
Black: Rich Running.
Blue: Oil in the exhaust.

I guess grey is a combination of white & black so a car that hasn't been used for a while and has lots of moisture in the exhaust and is on the choke should run grey until it's been out for a nice long drive.

If it is using oil I have found the bit of the engine that I think causes it. The piston rings get a load of black carbon caked in behind them so they eventually can't move. I haven't cured it, or tried to cure it with a flush - it might work??? but have had very good compression and low oil use after rebuilds where I went in and cleaned it out but didn't replace rings or pistons.

Have you looked for leaks underneath yet?
 

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if its smokey under load and you think its a stuck ring then a flush may help
but if its valves then it may make it worse because the gunk could actually be helping control oil burning!
 

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Discussion Starter #4
Thanks for suggestions, first action will be to check forleaking valve seals, but what is a flush and how do you do it?
 

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To be honest, my 33 never uses oil, and if you boxer engine is using a lot you've probably got a piston ring gone, worn valves, or a leak somewhere :(
 

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Thanks for suggestions, first action will be to check forleaking valve seals, but what is a flush and how do you do it?
The trade seem to round on a product called Forte which is normally added to the oil just before it is changed. The engine is run for a period of time, maybe 15 minutes and the flush attacks and suspends the carbon deposits so they can be drained off with the oil.

That's the theory but the pinholes that go through the pistons to lubricate the rings don't really look like they would carry a high volume of oil so that plan looks a little impossible.

The second option is to put some diesel oil in the car and run it for 1000 miles. The diesel oil is more aggressive at attacking & suspending the deposits than normal oil and I've tried it on 2 cars about 2 years ago without any problems- I got the idea off a forum so I don't know if it is truly a safe technique to use. I used cheap supermarket mineral based diesel oil at £6 a can.

Finally you could strip and rebuild the engine which is not a bad job at all on the Boxers- either with the engine in or out.
 

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If your rings are gunked up then a good, long, hard drive should shift a lot of it. Need to get the motor up to full hot working temp and plenty of revs to do any good. I know many years ago some people used to put a shot of Redex down each spark plug hole and leave it over night. This used to loosen and help dissolve the crud around the rings and head. Only problem is it blows out heaps of blue smoke when you start up next morning!
 

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What is Redex?

My 33 will never use any oil (despite very uneven compression - go figure!) except sometimes when restarted after being parked on a sideways slope.
 
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