Switching to synthetic oil

[bsturman92]

Hey guys... Been running 10w-40 conventional oil for few years now.. Been wanting to switch to synthetic but read good and bad reviews... I have a few leaks already so what would u guys suggest?

[bmwman91]

Mobil 1 15W-50, change oil every 10k miles, Mahle filters every 5k miles. Done. This assumes that the car sees street duty and maybe an autoX here and there. If you track it, then change the oil more often.

M1 15W-50 provides the best protection for your money when it comes to street oils since it has high zinc and phosphorus levels, which many oils lack these days. Castrol 10W-60 TWS oil is better, but ungodly expensive and completely unnecessary for a stock m42.

[bmwm42]

15 40 or 5 40 synthetic is what i run 15/50 is way thick imo

[bmwman91]

15 40 or 5 40 synthetic is what i run 15/50 is way thick imo

It is thick, but it also recommended in the manual for a reason. Directly actuated bucket lifters require higher quality oil. Thanks to an EPA change in 2008, Mobil 1 15W-50 synthetic is one of very few oils left with reasonable amounts of ZDDP. The thicker oil is not robbing any measurable amount of power or fuel economy.

[bsturman92]

I have been running Valvoline 10w40 conventional the entire time I have owned the car.. I have read that switching to synthetic will increase the chance of leaks.. especially if I already have some...... can I just switch over to synthetic whenever I want.. drain what I have and fill with synthetic?

[bmwman91]

Yeah, synthetic will leak a bit more. You can make the switch any time if you do decide to do it.

[M3Philipp]

But a 15w50 full synthetic, will not leak more, than a 10w40 half synthetic, or even a 10w40 mineral oil, right?
It is even thicker when cold, thicker when on temperature, it should leak less, or am I wrong?

[brianf408]

Switched to Castrol 10w40 full synthetic on my last change, and I haven't leaked any more oil than with conventional oil. Definitely make the change.

[M3Philipp]

Are you sure? I think FULL SYNTHETIC 10w40 does not even exist.
Full synthetic is atleast 0w40 or 5w40 im sure, 5w40 most of the time is an hydrocracked oil, while 0w40 should always be a full synthethic one.
While 10w40 is either a mineral oil, half synthetic one, or hydrocrack one which is similiar to half synthetic.
By the way Im running Castrol TWS 10w60 on my m42 now.

[noid]

Forget synthetic, go 15w40 shell rotella diesel oil. Rotella has tons of zddp for our tappet engines.

[bmwman91]

Are you sure? I think FULL SYNTHETIC 10w40 does not even exist.
Full synthetic is atleast 0w40 or 5w40 im sure, 5w40 most of the time is an hydrocracked oil, while 0w40 should always be a full synthethic one.
While 10w40 is either a mineral oil, half synthetic one, or hydrocrack one which is similiar to half synthetic.
By the way Im running Castrol TWS 10w60 on my m42 now.

Mobil 1 makes 10W-40 full synthetic.

http://www.mobiloil.com/USA-English/MotorOil/Files/Mobil_1_Product_Guide.pdf

Forget synthetic, go 15w40 shell rotella diesel oil. Rotella has tons of zddp for our tappet engines.

Interdasting...

[M3Philipp]

Thanks BMWMan, I didnt know about this!

Another thing.
There is Castrol 10w60 RS, AND Castrol 10w60 TWS. However I bought TWS, but what is the deal with the RS? It is a bit cheaper, but not much.

[bmwman91]

http://castrolcrew.com/Community/?t=38

"When BMW first spec'd Castrol 10w60 for M cars it was back when the e46 m3 first came out in 2001 model year. It was the Castrol RS 10w60, a really high performance motor oil, ester-based and with a lashing of castor oil additive. A little later, when Castrol moved to make the 10w60 a PAO base stock, BMW "fixed" the ester formulation in the form of TWS. In its specific application, it is a tremendous oil - - you can't buy better."

[noid]

EPA regulations have drastically reduced the capabilities of gasoline oils over the years including the much needed zddp for our tappet engines.

Diesel oil is just like gasoline oil, expect it is not regulated as toughly.

I know numerous guys who use Rotella T in powersport racing engines (powersport engines are also tappet engines.). These engines live their whole lives at 10,000rpm and I can attest to the capability of this dirt-cheap-yet-awesome oil.

[TobyB]

Rotella has tons of zddp for our tappet engines.

Not anymore, it doesn't. "LE" Rotella has something like 800 ppm, not really enough.

The Mobil 15-50 is pretty good at 1200 ppm.

Or you can just put in a bit of ZDDP additive- several reputable cam manufacturers
market it, and they stand behind their cams... when used with it.

fwiw
t