Valvoline R&P 5W-30, 4K OCI, 2025 Subaru Forester
- Thread starter PWMDMD
- Start date
I know it’s not like for like, but the head temps on my Harley run 265 unless it’s crazy hot (95+ degrees) and I’m doing 80 on the interstate, then it’ll run at 285. If I hit stop and go traffic on the interstate in those temps, the heads will climb as high as 305 with the coolant cresting 225 (coolant only cools exhaust valve seats), so my oil is somewhere around 250+ regularly. I did 20k on HPL this last go around in those conditions regularly. I wouldn’t sweat oil temps in the 220s with a modern quality synthetic.
Most oil temp is taken from the pan or along the main galley near the filter, somewhere it'll remain submerged. An oil pan temp of 230°F is nothing to worry about. That's the upper end of what I aim for. (210-230°F) This is assuming you're using a half-decent synthetic oil that meets spec.
If the pan temp is 230°F, the bearing temp is likely ~260°F (typ. +30°F rise in commuter car) which isn't alarming. Note that using a higher grade will increase this temperature due to a combination of reduced flow across the bearing and increased hydrodynamic friction from the higher viscosity. (however slight) This increased temp could offset the higher grade in that the oil will thin down to the same viscosity as the OEM grade, just now at a higher temperature.
In either case, a better quality oil will give more peace of mind by way of less shear, better tolerance of fuel dilution, less foam/aeration concern, and better heat tolerance. Foam/aeration is a significant factor when it comes to heat as it can cause a substantial spike in oil temp. Given the higher heat capacity and thermal conductivity of PAO base oils, coupled with lower CoF targets, the oil is likely to run a little cooler (transfer heat better) on its own.
If the pan temp is 230°F, the bearing temp is likely ~260°F (typ. +30°F rise in commuter car) which isn't alarming. Note that using a higher grade will increase this temperature due to a combination of reduced flow across the bearing and increased hydrodynamic friction from the higher viscosity. (however slight) This increased temp could offset the higher grade in that the oil will thin down to the same viscosity as the OEM grade, just now at a higher temperature.
In either case, a better quality oil will give more peace of mind by way of less shear, better tolerance of fuel dilution, less foam/aeration concern, and better heat tolerance. Foam/aeration is a significant factor when it comes to heat as it can cause a substantial spike in oil temp. Given the higher heat capacity and thermal conductivity of PAO base oils, coupled with lower CoF targets, the oil is likely to run a little cooler (transfer heat better) on its own.
Wasn’t aware of that with the PAO base oils. Thanks for the info!
I'm guessing that a much thinner oil was used the first 1400 miles and that it wasn't all drained very well before the VRP was filled.
I don't think (yet) that VRP has a reputation for shearing really fast, so that's the only other explanation I can think of. Either that or it truly is shearing like mad.
I didn't account for the residual OEM oil being a 0W-16. That was my mistake.
The dilution aside, I wasn't suggesting VRP sheared a lot but rather that Blackstone's KV100 is wrong. (which it is at least half the time)
There are examples of VRP 5w30 holding viscosity on other UOAs. Initially, I too was concerned about shearing but having seen some good UOAs my concerns are mitigated.
Subaru FB25 oil temp sensor is after oil pump and before the oil filter on the front timing chain cover. Highest I've seen was 261 while towing. Winter temps 190-205 summer temps 210-240. 2018 Forester 6mt.
Dang! Newer ones must run warmer. Only times I’ve seen 230 degrees on my 2.5 was climbing the passes in the cascades or down in Oregon on mt, hood/jefferson.
This test was done at Polaris Labs, I think they have 3 locations. Call them back and ask for "a new interpretation". The have no problem looking at it again and maybe by another analyst.
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I do live in mountainous terrain. This explains part of the reason why Subaru’s are hard on oil.
Thank you for posting this, Wintertime 5W-20 would be fine, but 5W-30 would be better. Summertime, kind of pushing it on 5W-30, but 5W-40 would be perfect.
SuperCar 0w30 would deal with it fine, and likely have somewhat lower temps too.
