Kill me now, bought a 06 750Li with 53K miles tonight.....

[AuntJemima]

So I resisted buying an E66 because of all the horrors discussed on this board and input from "white" the BMW mechanic in GA that all E66 need valve stem seals an gaskets at 70K+. Have instead been paying independent to fix my 1995 740iL with 156K miles which I love.

Saw an 2006 750 Li with 53K miles and put in a low bid ($10,000). Seller accepted the bid (!), so I test drove it and tried to get it to smoke or downshift bump for 30 minutes of spirited driving. Could not get it to do anything bad and it drove like a dream, so it now sits in my driveway...

I didn't have it inspected by a BMW dealer, did that when I bought my 95 e38 and none of the stuff the dealer said was broken ever became an issue in 15 years.

I wonder if anyone has used or made a valve stem seal oil additive to prevent failure?

Wish me luck...

[377Z]

Looking forward to pics neighbor!

[xfactor490]

53k is kinda early for valve stem seals to fail. Easy way to check; after the vehicle is fully warmed up let it idle for 10-15 mins, then flash the accelerator. Check the tail pipe for white smoke. If it needs them look into doing it with the AGA tool, or find a Tech in your area which uses the kit. Saves a ton of money and time. Either way you got a great car, mines got 236k on the clock.

[AuntJemima]

Thanks xfactor,

No smoke so far. I am interested in avoiding valve stem seal failure by any method(s) available. Perhaps a different oil or additive, the only thing I can think of.

[377Z]

IMO something that goes a great way towards extending the life of all rubber/plastic under the hood is a cooler thermostat. BMW seems to have made the US cars run hotter than the EU cars, probably due to either emissions or fuel econ reasons. Not sure if it would specifically help with valvestem seals (I bet some would argue no since I've seen some claims the factory seals were flawed from the getgo--and they may be right, IDK), but it certainly can't hurt. An actual oil cooler would probably help more, but this was way easier to do.

[xfactor490]

Unfortunately it's only a matter of time. They all fail. However, I do see them lasting longer when switching to a 5w-40, or 10w-40 synthetic, and adding Lucas oil stabilizer. I've also got a 04' X5 with the N62 engine, it just turned 171k. I haven't had to do the valve seals yet, its just starting to smoke a little from bank 2 tail pipe.
I don't know of any thermostat options. The N62 has a MAP thermostat, its controlled by the DME.

[377Z]

IIRC there is some resistive heating element in the thermostat that can locally heat it a tad to open it sooner under certain conditions , but its still built around a basic mechanical thermostat.

They can be DIY modded (I think its detailed elsewhere on these forums) or you can find modified ones on ebay. I think stock opens at 103C, the cooler one opens at 90C. Since its a product from a non sponsor I don't think we can link it, but its a search away.

edit: forgot to mention--I tried the liquimoly based on reviews here, only been in for ~500 miles. Cut down on the smoking a lot (almost completely), but I can still smell it after a long idle. Still pretty good for a fix in a bottle, which I rarely try.

I might try the lucas next since its in local stores.

[AuntJemima]

377Z,

Is the Liquimoly an oil or an oil additive? If an additive, how much did you use, and what oil do you use? What were you using before when it was smoking? Are we BMW owners an anal lot or what?

I have run Mobil 1 full synthetic in my e38's engines and half Mobil 1 in my transmission (other half original factory fill) for 15 years and have never had an oil or trans fail.

IIRC there is some resistive heating element in the thermostat that can locally heat it a tad to open it sooner under certain conditions , but its still built around a basic mechanical thermostat.

They can be DIY modded (I think its detailed elsewhere on these forums) or you can find modified ones on ebay. I think stock opens at 103C, the cooler one opens at 90C. Since its a product from a non sponsor I don't think we can link it, but its a search away.

edit: forgot to mention--I tried the liquimoly based on reviews here, only been in for ~500 miles. Cut down on the smoking a lot (almost completely), but I can still smell it after a long idle. Still pretty good for a fix in a bottle, which I rarely try.

I might try the lucas next since its in local stores.

[377Z]

Liqui Moly 2020 motor oil saver. It’s like a $6-8 additive. Mine would actually make a cloud, so I figured $8 was worth a shot, particularly with the positive reviews here.