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Shadow86325e
04-10-2010, 07:45 PM
I went to a mechanic to diagnose my misfire problems, he said it's the oil, that it's too thick and is causing lifter issues.

how true is this?

I can't help but be a bit skeptical.
flyfishvt
04-10-2010, 08:06 PM
What are you running for oil? How old is it? How much experience has this guy had with BMW's? After working on virtually every part of this car I almost believe him. They are a different beast altogether. I suppose anything is possible.
albaby
04-10-2010, 10:48 PM
i used to run 20/50 with no prob - in NC, it's mild here, check the temp ratings against where you're at
CrazyCoder
04-10-2010, 11:13 PM
How old is your oil and what weight is it? 0_o

I've never had a car misfire do to too thick of oil causing 'lifter issues'. What kind of issues? The only type of lifter issue I know if is when they 'collapse' (fail to build hydraulic pressure) which results in a lot of ticking. Usually the fix for that, short of replacing the lifters, is to run thicker oil.

Do you trust this mechanic? Sounds to me like he's blowing smoke. Still, if you're due for an oil change, then you should do one anyway. Also, for misfire issues, check your spark plug boots to see if oil isn't seeping out of the valve cover gasket and shorting the plugs out. It's fairly common and an easy fix (IE: New valve cover gasket).
Shadow86325e
04-10-2010, 11:37 PM
fresh oil, 20w50. full synth.
CrazyCoder
04-10-2010, 11:55 PM
fresh oil, 20w50. full synth.

Mechanic is an idiot. He's probably one of those '10w30 goes fine in everything' guys.

Try checking the coil tubes (the bit that connects the coil to the spark plugs) for cracks or oil submersion. Also take a look at the flexible intake hose between the throttle body and the MAF, sometimes it cracks and can cause unmetered air to get into the engine, leading to a lean condition that can cause misfiring.
Shadow86325e
04-11-2010, 12:47 AM
yeah vacuum is my guess. these cars are vacuum dependent.

I just need a garage to work in. I have one, but it's full of cats who piss on anything.

who wants a kitty?

also misfires only when cold, with slight missing when warm, otherwise it runs great.