My 2005 Tacoma specs 5W-30, and I'm running Valvoline Advanced FS ... engine sounds good. Running xW-30 in your 2015 Tacoma is a good move IMO.
Why we should love HTHS specs:
- Thread starter tundraotto
- Start date
I've used Valvoline FS and several versions of M1....all 5/30 for it's entire life. My next service at 90k I think I'm going with Maxlife FS 5/30 or 10/30.
thanks for the link ZeeOSix, an EXCELLENT read + it answered some questions for me about the affects of a lot of VII. i thought there had to be downsides + previously read about the different VII's used today another reason i mostly stick to a 10-30 in PA as that minute fuel savings is NOT as important as engine longevity!!
Looks like cruising down the road with some HTHS 2.6 or less oil at less than 3000 RPMs will make your rings last almost forever! The 3000 RPM box wear is at ZERO!
My car specs 0/5w-20 but mentions an oil of higher viscosity may be better suited for high speeds or extreme load conditions (or as GM says, "track days") Kinda makes sense now.
What interests me is how much the temperature (130°C) impacts these results. The HTHS is a given variable at 150°C. Let's take another oil that's on the lower end of the HTHS scale, something like a 0w-8 with a KV100 of ~4.5 cSt and HTHS of about 2.2 cP, but run it at say 60°C. Given a variable in temperature, there will be variation in specific heat capacity and variation in additive response and reactivity, both of which are also variable depending on which base oils are used. Would the results be the same, or at least see a similar curve, if the temperature was scaled down?
An observation I want to point out is you can tell where the piston starts to spend more time in EHD and HD lubrication at or above 4000 rpm as the wear falls back down a bit. The piston speed is likely reaching that point where the piston begins to plane on the oil film more so than shoving it away. That point is going to differ with every engine due to variations in rod length, stroke length, piston design, ring thickness and tension, load, etc... It doesn't specify the load here. What if the test is done with a simple 50 lb-ft steady load to get one result at each steady state rpm and then doubled to 100 lb-ft load, increasing the heat and pressure seen by the pistons and rings similar to towing duty or driving up a long incline, would the results be the same?
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Gotta look at the curve fit - the solid lines for each RPM. Wear increases at every RPM above 2000 RPM at right around the 2.6 cSt point.
Yes, lots of variables. But seeing similar date about ring wear vs HTHS, it seems like piston rings are more sensitive to wear as a function of viscosity and RPM than other parts of an ICE.
That's true, and also note that thinner, lower tension rings are more sensitive in every way compared to thicker, higher tension rings. With thinner rings, you'll see a more drastic change in power lost to friction as HTHS increases and at very high piston speeds (avg = >30 m/s), can upset ring seal. We're talking 0.7mm rings with 6 lbs tension in engines turning >8500 rpm though. A passenger vehicle, with a typical 1.2mm-1/16" ring pack, cruising along at 2000 rpm, likely won't notice much difference.
Yep but it also depends on the type of VII used. IMO this limits the usefulness of something like the HTFS ranking. Never mind the fact that we have no idea what HTFS is considered "insufficient".
A VII could have a shear stability index of 10 or >50. VI polymers like Shell's star polymers are pretty rock solid.
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