darbyhood wrote:I use Mobil 1 Synthetic 5w30 in the summer and Mobil 1 Synthetic 5w20 in the winter and have no issues.
You're gonna break something like that. At the very least, you'll wear your cam down to nothing. Unless of course, you're puttering around in your E28 in Northern Russia where its -20C all year
The older motors have bigger variations as machines didn't machine as well as they do today and the use of the really thin oils is for those modern machines that can use them properly and benefit from the lower power loses from using the thicker oils.
M30s need thicker oil. 20W-50 is spec'd to low temps and 10W-40 is spec'd to almost as low as would be necessary anywhere below the arctic circle. From the manual (did I already post this in this thread, I ain't gonna look):
20W-50 15°F to 122°F
15W-50 -4°F to 105°F
15W-40 -4°F to 85°F
10W-50 -20°F to 68°F
10W-40 -20°F to 50°F
10W-30 -20°F to 40°F
5W-30 -40°F to 22°F
5W-20 -40°F to 15°F
So that 5W-30 used in the Canadian Summer is only good protection to -6°C. That is not protection!!
I started out with M1 15W50 and always liked it; 'course there are some BMW techs who simply don't like Mobil and will either insist on Castrol since "it sounds better" or a dino oil, Brad Penn or Valvoline, which I just can't use (sorry). A couple of years ago I switched to a 0W40 Redline for one winter, because I was trying to find a year-round oil, what with winters in Colorado, but my usage went up dramatically (and the previous post may have it right - although in fairness to Redline they didn't enthusiastically say yes, and their rate of evaporation on this oil is very high). Then I switched to Redline 10W40 for year round use; it was okay, I think would be great year round in Colorado (I try to change oil once a year if I can do it) but then, being in Texas, what with the higher ambient temps they have down here, the Redline will thin at temp to a good 40 weight, and I have come to the conclusion that higher temps in this engine, the M30, really do need an oil that won't shear out of grade, i.e. a 50W that becomes a low to middling 40 weight. Seems the M30, in high temps, likes that 50W, I finally have to agree. Actually, Redline does spec 10W40 for our cars (M20, M30) because it acts more like a 50W, but with the higher cost, I've come to think, why?? Plus, and this is interesting: Redline stains engine interiors - with Mobil 1, the cylinder head internals stay bright, and with Redline, they turn golden - I had a chem engineer say it may be because of the dyes Redline uses.
I bit the bullet and went back to 15W50 M1 for now - at $25.46 for five quarts in the jug, it's hard to argue with that logic. Seems quiet to me, and if push comes to shove, I can always use 10W40 M1 if I'm in Denver, although I used 15W50 M1 for years year-round and I can't see that it hurt anything. And 10W40 M1 thins to a high 30W at temp.
I've got a UOA sample ready to go out, 10K on Redline 10W40, if I remember I'll post the results when I get it back..
EDIT: I got the UOA back, and was mightily surprised at just how good Redline 10W40 looked after 10K, I've posted it in a separate thread..
Last edited by BRRV on Apr 22, 2016 11:32 PM, edited 1 time in total.
I use good old Castrol GTX 20/50 in our E34 M30 535i. It has used this oil type almost since new and now has 462,000 miles on original engine. Everything clean when removed head 15,000 miles ago for new gasket. Uses about 1/8" down dipstick between oil changes at 3-5K. No additives used.
Apologies if I'm opening old wounds, but... why do some people recommend Rotella T6 oil? It's a synthetic diesel oil. (and it's not the first time I've seen people recommend diesel oil for gasoline engines)
On my M5, I use both Castrol GTX and Valvoline VR1.
With the changes in the ZDDP in oils, much less, to save cheap catalytic converters, folks have been looking for oils that still have enough of the stuff to avoid excessive engine wear in older vehicles.
You're gonna break something like that. At the very least, you'll wear your cam down to nothing. Unless of course, you're puttering around in your E28 in Northern Russia where its -20C all year