I recently changed my Denso plugs for the proper NGK's, and after only 500-or-so miles on the Denso's, the plug on cyl 5 had some oil on it; when I changed to the Denos from the first lot of NGK's there was a bit of oil on plugs 4, 5 and 6. I've changed up to 5W-40 oil (from 5W-30) to see if this helps, but if it does not, I've been advised to try a "piston soak" at my next oil change because oil control rings are known to stick on the M54. I wanted to see if anybody had done it before.
It was explained to me as follows:
remove plugs and pour 10 ml of some sort of injector cleaner (I've already got some Liqui Moly 1803, so that's the one I would use) into each plug hole,
leave as long as possible, but at least overnight,
disconnect DME and fuel pump and turn the engine over a few times with the plugs out to get the cleaner out of the bores,
change the oil immediately
I have done the CCV test (no vacuum when the oil cap is removed, and air comes out of the filler when I blow into the brake booster hose), and plugs 1-3 were all clean so I must assume the CCV is working correctly.
Is this piston soak safe? If so, has anybody got any data on the results?
Thanks,
M.
It was explained to me as follows:
remove plugs and pour 10 ml of some sort of injector cleaner (I've already got some Liqui Moly 1803, so that's the one I would use) into each plug hole,
leave as long as possible, but at least overnight,
disconnect DME and fuel pump and turn the engine over a few times with the plugs out to get the cleaner out of the bores,
change the oil immediately
I have done the CCV test (no vacuum when the oil cap is removed, and air comes out of the filler when I blow into the brake booster hose), and plugs 1-3 were all clean so I must assume the CCV is working correctly.
Is this piston soak safe? If so, has anybody got any data on the results?
Thanks,
M.