anything wrong with running a dino 5w30 in my m50?

[ryan roopnarine]

yeah, i should know better. i just bought about 2+ cases of 5w30 and 10w30 albertsons brand and formula shell brand motor oil from an albertsons closing sale. if they go down to 75% off, i'll go back and pick up the rest of the SAE 30 and SAE40 oil they have on the shelf for $.45 each. between what my mother and I bought, we have at least 72 bottles of motor oil sitting in her garage, as well as a case of tranny fluid. there also resides a gm 60 degree v6 that needs to have its oil changed every 500 miles to desludge/decarbon it, so the oil might get used quicker than i think.

at any rate, i needed to change my oil about two weeks ago. having an abundance of the xw30 around, i decided to try some chateau albertsons 5w30 and a bottle of fomula shell to round it out. these are all SL grade oils. figured that it if it started to make noise, i could change it out. i usually use nothing lower than 40weight, or a fat 0w30 germal castrol syn oil. i stopped using mobil 1 5w30 about two years ago. anyways....got the car onto the highway aaannnnndddd.....

about .7 mpg MORE! highway, and a solid 1.0 mpg improvement in bumper to bumper. i'm getting about 29-29.5 mpg at 70mph, 28 at 75, 26 at 80, 30 at 65 mph and 32 at 60, all with the a/c on 100% all on the same 100 mile stretch of road. (all with EAT). i haven't had a chance to check 55 mph yet. i never did this well with mobil 1 5w30, and two years ago SL was already out. if it was SM, maybe i could attribute it to that. anyone care to comment? the car is desperately needing an Insp II, so it is doing this in spite of needing spark plugs and probably boots. anyone want to tell me that i'll grenade the motor by running this thin a dino in it? if that is the case, i'll stop. change interval is about 3500 miles. oil consumption is down from bulk 10w40. i think that you all can tell by the timbre of this post that i wouldn't mind keeping this fuel mileage, but i'll stop if i have to. ambient temps right now are between 80-100F (33-39C) during the day, its a high stress environment.


ps
at this point, i would run 0w20 in it if i had a free oil analysis laying around, and see what it did, if only to post over at (the oil place) and here.

pps
the alltime high for this car, when it was in exceptionally good tune, was about 35.5 mpg at 55 mph, with a/c on 50% of the time, no headlights or blower on if not necessary. i have the autotrans and the 4.10 rear end in my 525i.

[Ross]

I'm no tribologist but think 30w is too thin for 100F. My '95 owners manual suggests 15w- 50 or 20w-50 for temps exceeding 30C (85F?).
Dino oil is fine for me too but I change it at around 2500 and NEVER exceed 3K. The only time I used synthetic the motor began to weep from a few seals.
Your improvement in gas mileage demonstrates how much power it takes to pump heavy oil.

[Russell]

I am getting about the same mileage and I am using Castrol Syntec 5w50. I have also wondered about xw30 weight oil as I understand these older cars like heavier oil..

[ryan roopnarine]

the thing is, even in its best tune, it always got less than i'm getting now, in particular, when i got 35.5 mpg out of it. i intentionally have to drive into stop and go traffic every other day, about 80-120 miles per incident, and with the oil change, i now have a bottom MPG ceiling of 16.5, usually 17. this driving is with 100% ac on, aux fan running, lots of idle time even off of the streets. on the highway, the mpg gauge (OBC) usually sticks at the moving mpg when waiting 1,2,3 minutes at the toll booth on the 100 mi road on which i made the measurements, whereas before the mpg drop would be noticeably quicker. the car also arrives at the measured mpg faster on the highway. maybe its the vanos in your car?

[BillionPa]

you "should" be ok, but purchase a bottle of lubro-moly MoS2 oil additive and a bottle of Valvoline synpower oil treatment and toss em in there for good measure.

with the VSOT you should be able to coax another 1000 miles out of the dyno engine before you would want to change it (3500 miles), assuming you are of the spirited driving variety, and actually use your car for short duration trips.

remember, lower viscosity oil has more blowby, and thus a longer service life if the oil doesnt have lots of antioxidant and antiacid additives.