15W40 - why isn't it more popular/common?

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Sep 24, 2002
Now maybe there's an obvious reason I'm not aware of but (in dino) I don't seem to see this multi-weight all that much. I can find it in some parts stores in a couple of the major brands. But it's not in the big retailers nor in every parts store nor is it popularly private labeled like other more popular multis. It would seem to me to be a great all around oil and 15W40 does land squarely in the little temperature range bar in the owners manual on several of my cars. I'd think it would avoid the stigma of the old 10W40. To me this would seem the logical step beween 10W30 and 20W50. So what's up w/ 15W40? In popularity it doesn't seem to hold a candle to other dino multis like 5W30, 10W30, 10W40, 20W50. thanks, -T
For all the vehicles of my family members, the only one for which 15W-40 is recommended is my turbo Volvo in very hot weather. All the other recommendations are for 5W-30 or 10W-30. 15W-40 is the dino oil for all the diesel pickups on the road. I often see it in 1 gallon jugs, especially Shell Rotella-T and Chevron Delo 400 and often Delo 400 in quarts, sometimes Pennz. Agreed, 15W-40 would be my recommendation over 10W-40 or 20W-50 where suitable. Ken
Yeah I agree...basically 15-40 is a known diesel grade and since there are few diesels out there, it's not as popular (both in use and on the shelves) as 5-30, 10-30 recommended by most if not all new american cars....
I agree. Anything 10W40 can do, 15W40 should be able to do better ... except flow in chilly weather. My brother's bike (Kawasaki Ninja) calls for 10W40 ... and with a high-revving engine like that, you'd think a 15W40 formula with fewer VII would be better (more stable). I was thinking Supreme 7000 synthetic blend for this machine. But, he's not one to experiment so I bought him some Micron Moly 10W40 instead. This should be a significant improvement over his Castrol GTX which only has a trace of moly ... if that. Most people associate the weight 15W40 as the standard heavy-duty (fleet) weight for both gas and diesels. --- Bror Jace
pgtr Maybe not popular in CAFE U.S.A but sure is here. Even though 20W50 the clear leader 10/15W40 taking share away. 10W40 Redline their big seller here, a big change I think?
Just like I mentioned in another post a few minutes ago, it all boils down to what the car makers recommend. Oils like 15w40 are popular with people like us, however the average person just goes by their manual, or by what the dealer says.
0w40, 5w40, 10w40, 14w40. For the average consumer, the price/performance ratio is about equal, true the 15w40 will be a little better, but really how much?? Sounds like more hair splitting to me, but isn't that what were here for??? If you are using a high quality oil, like mobil 1 redline, or Amsoil. The 0w40 and 5w40 will outperform all conventional 15w40's
15W40 My son's Mercedes calls for a 15W40 in summer and no less than a 10w30 in winter. We recently switched from Amsoil AME to using Schaeffer's 7000 Supreme, 15W40.
At 17.4, isn't Mobil 1's 15W50 at the low end for a 50 wt? Maybe more like a 45 wt? Is there any difference in additive packages over their non-"racing" oils (their 0W40 "Euro" or 0/5/10W30 USA flavors) that would make the 15W50 less desireable for long drains?
Most racing oils generally speaking (there are some exceptions) have lower dispersant/detergent packages with higher levels of FM/AW additives. One could use the 15w50 and do short UOA to see how the oil was holding up.
I don't think M-1 markets the 15-50 as a "racing oil" (as Redline does with certain oils), it's just part of their nomenclature no different as calling the 10-30 is a "higher mileage" oil...
I think a lot depends on what area of the country you're in and which industry segment you're engaged. For example, if you are in the trucking or farming segment, 15W40 is your staple as in Shell Rotella 15W40, Amsoil 15W40, Chevron Delo 15W40, or Delvac 1 5W40, or Schaeffer's 15W40.
Thanks! Based on what I've read in this thread it seems all the more shame it's not more prevalant here in US compared to 10W30, 10W40 and other 'popular' weights. For that matter if an owners manual lists 5W30, 10W30, 10W40 and 20W50 as options dependant on typical temperatures, I dont' see 15W40 being a problem. Just my opinion. -T
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