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Why do some say to set the valve clearance at .010 and others say it's better at .012 ???? Which is correct?

Intake .010 Exhaust .012 is what is used on b35 motors, not sure why

I meant M30 motors.

On early M30s, clearance was spec'd at .010-. 012. E28 era M30s were spec'd at .012- ,014. I'm not aware M30B35s had a different spec for intake and exhaust, I believe they're the same as E28 era engines, but it's possible.

My b35 guru recommended it, 88 635CSi motor.

If I can offer an additional suggestion:

Not aware if everyone here knows about ZDDP additives to motor oil. The elevator speech is that ZDDP additives assist flat tappets (our engines) by creating a thin anti-wear surface on metal parts that come in direct contact with one another. Essentially, the added heat caused by metal-metal friction causes ZDDP compounds to form an anti-wear coating at the site of the friction.

Here's an AMSOIL article discussing whether older engines need oil with ZDDP additives:

https://blog.amsoil.com/do-older-vehicl ... motor-oil/

I will most certainly be running ZDDP additives in Eleanor.

Mike

I use a ZDDP additive and Valvoline VR1, which is high in zinc and phosphorous. The VR1 product sheet specifically says it's not for use in cars with catalytic converters. But the story is a little more complicated than that. Cats have been on US cars since 1975, and before the early 2000's, all oils had much higher zinc and phosphorus content. Oils were reformulated to lower zinc after cheaper catalysts were found in the early 2000's to replace noble metal catalysts, and zinc was found to foul these new catalysts. So if you have a 528i with an OEM-grade 3-stage catalytic converter, It doesn't seem that zinc will foul your catalyst.

I do think that lower zinc and phosphorus are not good for a flat tappet engine. But most of us change our oil frequently and put relatively few miles on our cars between changes.

I have found VR1 20W-50 to be quieter in the valvetrain than the conventional oil it replaced in my car, but to be fair I was running 10W-40 previously. For the record, my cat was deleted long ago.

-Eric

More on issues with oil and cats. Sometime around 2000 manufacturers started using low tension piston rings in an attempt to get a tiny bit more MPG. In doing so oil consumption often went up, sometimes dramatically. A quart a thousand or more. At those levels cat damage can occur when using higher ZDDP oils, but if you're not burning oil, it's not a problem!