M1 OW-30 vs. M1 OW-40 What's the diff?

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Mar 19, 2004
Lakewood, WA USA
Besides the 40wt part I mean, thinking of (for new new Japanese Mazda Miata ride w/1.8 DOHC), possibly squeezing better mileage/start up protection w/ M1 OW-30 vs 5W or 10W? I know the OW-40 is thought of highly here (and I'll use it w/ my 9500 mile LT1 powered Impala SS)...the Miata is usually "short trips", 6K miles or less annually, with temps rarely (sometimes) below freezing and rarely (sometimes) above 90'F.. [Cheers!] [Bang Head] got some $3.99 M1 coupons to use so I want to get a couple cases thsi weekend of either Ow-30/5w-30 or 10W-30 for the Miata...??
Go with the M1 10w-30. No Viscosity index improvers and a higher HT/HS of 3.3. Mobil 1 0w-30 (regular) is a very thin oil for maximum fuel efficiency and cold temps. No use using it in your case IMO. [Smile]
On a newer engine, particularly, I'd go with the M1 0w30. But I'd change it out at 5000 miles as I'm not sure it has the longevity of M1 0w40, which is rated BMW LL-01. Your driving conditions also lean toward a 0w30 oil, I'd say. The idea that 0w30 is only for cold temperatures is hogwash; it performs well in the summer heat, too. I currently have it in my Audi allroad 2.7t and it performs great. I find AutoZone and G.I. Joes to be a good source of oil in the Pacific Northwest. As far as the difference between M1 0w30 & 0w40, M1 0w30 is rated ACEA A5 & 0w40 is rated ACEA A3 -- the 0w40 has a higher HT/HS. The 0w40 is probably better at extremely high temperatures and holds up better after extended use (it's a Long Life oil). [ April 09, 2004, 03:38 PM: Message edited by: williar ]
Well there's the fun of this board, no different opinions, how bout that, .....BTW Autozone coupon expires this weekend (sat PM) M1 $3.99 a (US)quart, if I can get the military exch [Cheers!] [Eek!] [Big Grin] ange to match it, I save the 8.8% tax too, got two coupons so my gal can buy one case too...the OW-40 for the LT-1 that's only driven about 1K miles a year....more differing/agreement please! [Cool]
I'd go with the 0W-40. It has a nice HT/HS of 3.6, and still flows well when cold. I've used it in my '95 Accord and never noticed any decrease in gas mileage...
[Cool] I put the 0w-30 M1 in my 4.0 SOHC Ranger for the winter (it does short trips), I'll change it out soon and post a UOA.
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