Recent content by just_me

I'm well aware of the various states of lubrication. Walk me through the fluid dynamics of why flow isn't lucubration; it certainly not the whole story, but i'm looking for analysis, not dogma - ergo the open ended questions asking if any are able to go through the theory step by step. I'm...

I do find it interesting that Redline's 5W40 has such a margin in HTHS vs similar grades from M1 and Castrol/Edge. yes I checked:-) I note that the same cannot be said for other "premium"brands including most of the German ones or Amsoil. If HTHS is as useful as normally presumed, their 5w40...

I went back and did more reading (not on oil related sites!) on viscosity. Not having truly studied fluid dynamics, the **implications** (which is what we care about) of what I'm reading is still elusive. I now have several definitions that I'll simplify and consolidate into "an arbitrary unit...

The HTHS def was from the abstract/summary of the ASTM method (i don't have login priv for the full method, which i wanted). Viscosity was from deep memory in physics, and from some recent documents i perused trying to unravel seemingly conflicting positions - i don't recall where. Good to see...

I think I'd benefit from your version of the same topic, step by step. Along the way either support or slay sacred bovines, please :-)

quote: "From the above a 0W M1 does not appear to provide sufficient protection in high temperature scenario and a 15W50 is used although with an ester based oil a 5W or 10w can be used." I see that it's HTHS is lower. I do not see any evidence based threshold, so i see nothing to tell me...

Quote: "3 - Racing viscosity It is well known that the heavier viscosity oils such as10w-60 Helix Ultra are more tolerant of fuel dilution than the lighter 5w-40 versions. They usually have a much higher HTHS viscosity too" I track and occasionally race a street-legal, but fairly dedicated...

Originally Posted By: Dominic naa actually its a GM engine, the popular 3800-II, and is spec'd to run that high. Thanks though Coming to this discussion 12 years late, where does one find such a spec? I've never seen a spec (in either ideal viscosity meaured in mm^2/s) nor lbs/1krpm for any...

One of the big advantages of synthetic is that they flow better cold, and retain viscosity hot. So yes, its "thinner" when its freezing out, but at operating temp it should be more viscosity stable. In the end, i think you are dealing with minutia here... just use a good 5w30 and move on

As most have said, in an ideal world 5w50 is equal or better under all circumstances than hte 20w50. But this world is not ideal. I bet if you look at the specs for reach, you will find that, while both are "50" weight at high temps, the 5w50 is not as heat stable as the 20w50. I suspect they...

.. is that it has to make a bunch of assumptions, such as "95% of all people will just rev it up and drive immediately" - the only safe assumption. Are you willing to be different? Then of course, there are vast differences in motors - clearances, etc. What's appropos for a 1970s sports car at...

I just wrote the long version of this answer elsewhere on BITOG. But lightly used vehicles tend to accumulate water, fuel, and acids at much faster rates nad you need to get rid of them. IN many ways its worse than regular use. Those contaminants are eliminated by boiling and burning them -...

truth is, it really depends on how careful you will be during warm up. I expect it could idle or lug around at low rpm at very low temps, since oil pressure is usually proportional to RPM.

They occur over many years - either accelerated basic wear, or sludging, acid pitting, etc., that results in accelerated wear. Maybe in extreme conditions (like track use with a light oil) you'll have complete barrier failure and a meltdown/explosion, but that's not a normal circumstance. So...

My first question would be "how has the existing regimen worked". While we hear lots of "I tried X and liked it", its mostly nonsense. You only find out if things are good or bad after many, many miles (or when it survives extreme conditions). High mileage oils are basically designed with two...