Spiffyjiff

maybe someone else has run across this...

previously (about 30 days total), my track oil temp had always been around 225-235, no matter what track, no matter how hot the day. before the start of this season, in addition to a new OEM clutch, i did an ECU tune (not softronic, but was done by reputable shop) which increased HP/TQ by about 15/10 at the wheels, as well as swtiched from mobil 0w40 to redline 5w40. for my 2 events so far this year, my oil temp was 250...in sub70's weather.

any ideas for the jump in temp? could it be the tune or the brand switch? (i'm thinking it's obviously not the "0w" vs "5w" as that indicates cold operating temp viscosity etc.) i know 250 track temps are not uncommon BUT i find it hard to believe i'm THAT much faster/harder on the car since the end of last season, or that my radiators have suddenly clogged/taken a crap. my OCD self would just like a reasonable explanation.

thanks for any thoughts...

cbzzoom

It's not the oil. It could be the tune, if they are increasing power at high RPM they are probably doing it by burning more fuel.

Have you cleaned your radiators recently? Those front scoops can eat a plastic bag very easily.

You could also just be driving harder. 250 at the track is not anything unusual, as long as the temp comes down when you do the cool-down lap I wouldn't sweat it too much.

Spiffyjiff

agree on all points.

rediators are clean - already checked as i suspected them first as the culprit.

and yep, temp comes down quickly on cool down lap/pit-in. this is the main reason why i'm not not totally manic about this - for if it stayed at 250 or higher "unusually" long after session, i would have had it in the shop by now.

what can i say, i'm somewhat of a hypocarndriac.

mrzoop

i think you would be very surprised how much difference that '5' really means in the viscosity of the fluid. '0' level viscosities were made popular in the last decade or so mainly as a means to 'enhance' fuel mileage. here's a quote from a recent article about the relationship of viscosity in a very sensitive engine... note the term 'excessive parasitic drag'...

i would suspect the 15 degree increase is related to both the fluid viscosity and the chip reflash. this is most probably making a few percent more HP increasing the internal engine temp especially on the exhaust side.

"Oil's Well That Runs Well

Believe it or not, botched oil changes have been a headache on both the first- and second-generation Prius. Toyota actually issued bulletins about these mistakes. Furthermore, specialists I know who have serviced the Prius since its introduction in 2001 said they've seen their share of trouble caused by shadetree mechanics as well as careless technicians. These oil-related problems remind us just how precisely these vehicles are designed and calibrated.

For instance, some people create excessive parasitic drag inside the engine by installing heavier viscosity oil. (For your information, Toyota recommends 5W-30 viscosity oil for all Prius models from 2001 to present.) This additional drag reduces both fuel economy and cranking speed. The correct cranking speed is so critical that if a Prius engine doesn't restart within the specified time, it triggers DTC P3191. Technically, this code means "Engine Does Not Start." But in this instance, it really means that although the engine restarted, it didn't restart quickly enough.

Here's just one example of the aggravation thicker viscosity oil causes. A Prius owner changed oil and installed 10W-40. Later, his car began setting the P3191 code, but only when the temperature dropped below about 32°F! He never thought to mention the oil change or the heavier oil. Meanwhile, the techs diagnosing the car never sought the vehicle history, either. "

utkinpol

you can consider putting on 3rd radiator, they are relatively cheap at suncoast.

cbzzoom

No, at track temps you are affected only by the second number in the oil spec. 5w40 is the same as 0w40. That's what multi-grade oil is all about.

Granted, the "40" is actually not a specific number, but a range, and it's a pretty big range. The 5w40 might actually be a lot *thinner* than the 0w40 at track temps ! We can't really say without knowing the exact specs on the oils.

But anyway, the oil is probably not the issue. There are lots of people who run w50 oil at the track without seeing big oil temperature increases.

Macster

If not the tune -- too bad you changed two things at once the oil and the tune -- then the oil.

Redline oil has from 0.6 to 1.2% zinc dialkyldithiophosphate which could work to make the oil 'thicker' (the additive is a metal) this thicker oil accounts for the increase in oil temperature due to increased oil friction.

If you want switch back to Mobil 1 0w-40 and see what the oil temps do.

Sincerely,

Macster.