quote: Originally posted by Dr. T: Guess this oil would answer my question: "what are BWM M3/M5/Enzo Ferrari driver's supposed to use in severe cold?" (ie. when a 10W isn't adequate)
Dr.T - I reckon up to 15kkms I guess. I don't really have any actual data as even though M1 5W50 is everywhere it isn't a factory fill from anybody I can think of. I'm using 5W50 Pennzoil Performax 100 in my Mazda turbo and best oil I've used in this engine so far but obsolete unfortunately.
quote: Originally posted by Gary Allan: Well ..then (and thank you btw) that makes the existance of a 0w-60 impossible UNLESS you can truly have a fluid get heavier at a higher temp. That is, the bottom end of 5w (which 0w would be assumed to be below) is lower then the lowest 60 weight "weight".
Well, if you look at 5w and assume (and I am assuming here) the 0w is below that spec, it falls somewhere at or below 17 CST @ 40 C ..yet 50 appears to peak out at around 19 CST @ 100 C. That means, if I read the chart correctly, that a 0w-60 would have to be heavier @ 100 C than it is @ 40 C. That is, it would have a viscosity increase at a higher temperature. This would truly make it the "Holy Grail" of oils ..thinner when cold ..slightly heavier when hot.
Well, if you look at 5w and assume (and I am assuming here) the 0w is below that spec, it falls somewhere at or below 17 CST @ 40 C ..yet 50 appears to peak out at around 19 CST @ 100 C. That means, if I read the chart correctly, that a 0w-60 would have to be heavier @ 100 C than it is @ 40 C. That is, it would have a viscosity increase at a higher temperature. This would truly make it the "Holy Grail" of oils ..thinner when cold ..slightly heavier when hot.
Okay, I see what you're talking about now. Here's where you're making your mistake: You are assuming that a 0w60 oil would have to have the the vis of a 0w at 40C. It wouldn't. It would have to have the vis of a 60 wt at 40C. It would have to have the vis of a 0w at the J300 cold cranking and cold pumping test temperatures of -35 and -30. In other words, a straight 0w oil is always going to be thinner at 40C than a 0wXX oil.
How about having a base oil or blend there of with a HIGH viscosity index (essentially what adding VII's to dino's oils enable them to extend their weight gaps, less or not required by synths), and has the flow capabilities to meet the cold and hot flow requirements?