lucas oil stabilizer vs. thicker oil?

[Ernest72]

2 nice UOAs at 25k and 50k using either Subaru 0W20 or Motul 0W20. At 68k, next one at 75k. DD and spirited driving. Some high revs, but no rev limiter.

[Bonburner]

Originally Posted by ZDan

I don't think anyone should be concerned about what the viscosity is at 40C.

it's useful for calculating viscosity curves ~

[7 skulls]

Originally Posted by Bonburner

it's useful for calculating viscosity curves ~

https://www.widman.biz/English/Calcu...erational.html

Find the viscosity of your oil online, plug it into the calculator. Add in the max sustained oil temp you see and bang. If your cSt answer is less than 7.5 (see my previous post), you need a thicker oil. If your already running a HD 5w30, then you need an oil cooler.

[ZDan]

Originally Posted by Bonburner

it's useful for calculating viscosity curves ~

I guess? But just from "0W20" or "5w30" you already know viscosity at 0C and at 100C. I wouldn't use the 40C number to extrapolate beyond that range.

On the hot side, you usually have an HTHS at 150C number to go by.
And on the cold side, if you live where it gets *very* cold, you have CCS and pour point temp.

[ZDan]

Originally Posted by 7 skulls

https://www.widman.biz/English/Calcu...erational.html

Find the viscosity of your oil online, plug it into the calculator. Add in the max sustained oil temp you see and bang. If your cSt answer is less than 7.5 (see my previous post), you need a thicker oil. If your already running a HD 5w30, then you need an oil cooler.

I think HTHS is more important than extrapolated viscosity for high rpm/high temperature operation at the track. IMO run oil with HTHS >=3.5 cP @150C and yer good up to pretty high oil temps...

I'm running Redline 5w30 (3.7 HTHS) at 275F max oil temp at the track for ~15 minute stints, ~4 stints per track day, and change it out after 4-6 track days. Your calculator says 6.3 cSt at 135C(275F). So be it... If I was running much longer stints or endurance racing, I might run an oil cooler.

[7 skulls]

[QUOTE=ZDan;3476240]I think HTHS is more important than extrapolated viscosity for high rpm/high temperature operation at the track. IMO run oil with HTHS >=3.5 cP @150C and yer good up to pretty high oil temps...

Can't argue with that either. HTHS 3.5 or more for the Castrol I run so I'm happy. Kinimatic viscosity calculations mimic well what i saw with 5w30 and with 0w20. Hated watching oil pressure drop off with the 0w20 at temps matched by the numbers. If I push the 5w30, I should see the same drop off somewhere north of 118C. No race tracks around here unfortunately.
I determined a while ago that the risks associated with a cooler weren't worth it for my usage and the numbers say I don't need one. Interested in your UOAs and oil pressures. Not being a smart ass. Really glad someone is out there running this car hard without a cooler.

[ZDan]

Originally Posted by 7 skulls

Can't argue with that either. HTHS 3.5 or more for the Castrol I run so I'm happy. Kinimatic viscosity calculations mimic well what i saw with 5w30 and with 0w20. Hated watching oil pressure drop off with the 0w20 at temps matched by the numbers. If I push the 5w30, I should see the same drop off somewhere north of 118C. No race tracks around here unfortunately.

What did oil pressure drop from/to?

I determined a while ago that the risks associated with a cooler weren't worth it for my usage and the numbers say I don't need one. Interested in your UOAs and oil pressures. Not being a smart ass. Really glad someone is out there running this car hard without a cooler.

Yer fine and correct to ask, but I don't have pressure data and haven't done UOAs. If I was worried that I was on the limits either way, I'd monitor, but I'm somewhat relying on UOAs done by others who have tracked without coolers, running similar max oil temperatures to me and haven't seen any unusual or worrying oil degradation or wear metals. For pressure, my understanding is that pressure drop at elevated rpm may be more due to restrictions on the intake side of the pump. https://www.ft86club.com/forums/showthread.php?t=134863
But same source says that "A stock engine can take 7,600 RPM all day long..." so I'm sorta counting on that as well...

42 track days and approaching 60k miles, so far so good
And a few of those track days were with 0w20 so on me for that!

[7 skulls]

With 0w20, I was seeing low 40s psi at redline and any temp above 105 C. This was probably fine (my UOAs said it was) but I always eased off when I hit 116 C and let it cool. So basically I could get 3 or 4 turns in the upper rev range. On 5w30, I see mid 50s psi up to redline at 118 C and can hang out at high rpm enough to tail a hard running K20Z3 for 15 minutes on a twisty road. Not a track day for sure but enough.
Read that thread on oil pressures. Not seeing the pressure sag at redline with 5w30.

[Bonburner]

Originally Posted by ZDan

I think HTHS is more important than extrapolated viscosity for high rpm/high temperature operation at the track. IMO run oil with HTHS >=3.5 cP @150C and yer good up to pretty high oil temps...

I'm running Redline 5w30 (3.7 HTHS) at 275F max oil temp at the track for ~15 minute stints, ~4 stints per track day, and change it out after 4-6 track days. Your calculator says 6.3 cSt at 135C(275F). So be it... If I was running much longer stints or endurance racing, I might run an oil cooler.

damn you hit 275F?
I can't get it past 100C/212F with my engine sitting +4k rpm for 20 minutes runs

[Dzmitry]

Originally Posted by Bonburner

damn you hit 275F?
I can't get it past 100C/212F with my engine sitting +4k rpm for 20 minutes runs

That claim seems a bit too good to be true. Much of this is based on outdoor temps of course, so if you're talking about cooler days, then I can I understand. But at 4k+ RPM's for such a long period of time and you're holding at 212F still??? Seems like if that were the case, not a single person would ever consider any type of cooler on this car as a DD.

[NoHaveMSG]

Originally Posted by Dzmitry

That claim seems a bit too good to be true. Much of this is based on outdoor temps of course, so if you're talking about cooler days, then I can I understand. But at 4k+ RPM's for such a long period of time and you're holding at 212F still??? Seems like if that were the case, not a single person would ever consider any type of cooler on this car as a DD.

Seems about right to me. Averaging about 6k rpm on track for a full session my car runs about 230 +/-10f depending on ambient. I am running a 613 core.

[Dzmitry]

Originally Posted by NoHaveMSG

Seems about right to me. Averaging about 6k rpm on track for a full session my car runs about 230 +/-10f depending on ambient. I am running a 613 core.

I possibly missed where he mentioned he has an oil cooler? I just assumed he was stock.

[Bonburner]

Originally Posted by Dzmitry

I possibly missed where he mentioned he has an oil cooler? I just assumed he was stock.

I got the basic oil-water oil cooler from subaru installed.

Sure my last run wasn't the hottest of days, it was like 91°F outside.

[Dzmitry]

Originally Posted by Bonburner

I got the basic oil-water oil cooler from subaru installed.

Sure my last run wasn't the hottest of days, it was like 91°F outside.

Got it, so you at least have that cooler, which is likely what is doing the work. Because on an 80 degree day, if I'm cruising on the highway at 3.5K RPM, I will see temps get to around 225-230F. Good to know it keeps your highway temps nice and stable, it's a definite next mod for me just to keep temps in a sweet spot.