theVcar

I always add 1qt of 5/30 M1 full syn. I don't like the 28psi so I want to add something a little thicker but compatible.
Thanks
David

Bill Dearborn

They have 10/30 but that is only thicker when cold. Same weight (30) when at temperature. If you want a heavier weight oil you could go to the 0W40.

Bill

Coach62

Like bill said 0w40. Walmart $25 roughly. Better oil with much higher zddp levels.
Next up from that is their 15w50.

Just got back from Sebring tonight. 0w30 ran 270 degrees plus on a cooler day
15w50 ran 248 degrees on a 10 degree hotter day

theVcar

I want to add it as that extra qt when at NJMP. Can/will it make a difference? Temps 265 about 15 min into session.


Added: 5w/30 is stock, so 5w/40?

Coach62

Won't make much difference but I'd go 15w50

onargaroberts

28 psi has nothing to do with film thickness or the oil pressure in the loaded part of the bearing. It may seem intuitively wrong but it's not a problem. It is the speed of the journal rotating in the bearing that pressurizes the oil and builds a "wedge" of oil in the loaded part of the bearing. You may correctly need a thicker oil at 100 degrees C but 28 psi should not be the factor driving your concern.

theVcar

Don't you think 100c is way too low for RR to even be a concern? Your saying thicker/ heavier is not what I need?

I'm at 265 F

Coach62

You're talking $40 worth of oil if you do it yourself. I went 5qts of 15W50 and 3qts of 0w40. This lowered my oil temp over 20 degrees on a 10+ degree hotter (might have been 15 degrees hotter) day with far more humidity also. I went from worried about oil temps to pleasantly surprised with oil temps.

Bottom line is if it doesn't help, you can change it again for cheap.

Coach62

Minimal if at all. Just be sure and change your oil after the event. Try the 0w40 and see if that helps, or do as I did and mix the 0w40 and the 15w50. Only downside to having that mix is my oil pressures at lower temps was pretty high, sometimes topping 100 psi. If you do this, just don't rev it at all until higher temps are reached.

onargaroberts

Yes, we're all at 265F or higher on the road course, that's normal. But 100C is the only high temperature point the petroleum industry uses for rating oils and you have to use that point to know what you're doing. If the viscosity is greater at 100C it will also be greater at 265F.

I don't know if you need heavier weight oil. You're original concern seemed to be driven by a 28 psi oil pressure indication at some unspecified engine speed which is not what I would worry about for the reasons previously given. The oil film just has to be thicker than the combined roughness of the journal surface and the bearing surface and the volume of oil being supplied has to be greater than what gets "squished" out of the bearing/s. Once these criteria are met, nothing touches.

In a well designed and properly functioning lubrication system, the measurable wear takes place on start up before the hydrodynamic oil film is established. After that, nothing much happens.

blkbrd69

Great work, now your getting the hang of it. I can almost here the addiction building.

Numbers like these put a crimp in the theory that a thicker oil runs hotter due to pump heating.
You are the second person in a few days that has informed me 50 wt actually ran cooler on track than 30 or 40 ????????

Coach62

That obvious huh?

The temp improvement was very significant I thought. After the first session I thought there had to be a mistake. My oil temps never once went above 248. If it had only been a couple of degrees it would have been one thing, but a 20+ improvement in oil temps is too significant to overlook - or even argue what the reason for the improvement was.

theVcar

Ok, it is not so much the psi. I thought I would mention that along with the 265* I am driving the car harder.

2006 orig owner 132k
Bolt ons: kooks,ceramic coated, HF cats spin ported 102 VR

WHAT ABOUT MY BEARINGS NOW

Olitho

I often like to play the contrarian. I don't know the answers to the questions posed here, but so e presumptions are being made that are not being validated by an expert such as a GM test engineer, F1 engine builder or an engineer specializing in lubrication and/or heat exchange.

I offer up an alternative reason why higher viscosity oils run cooler. Where is the tempo gauge? Is it after the EOC but before the engine? Maybe the higher viscosity flows slower through the engine oli cooler and gets to shed more heat before hitting the temp gauge? That is just a thought.

With regards to the statement about a 10-15 degree hotter day and the car running cooler despite higher humidity, that humidity might hamper our human cooling system based upon evaporation from our skin, but I think the density of the moisture in the atmosphere going through the radiator might actually cool it.

Like I said, I don't, but some very loose conclusions are being made in this thread without adequate testing and control measures.

Coach62

Fair enough, not sure about the humidity so ignore it. It's not like a bump in humidity is going to come anywhere close to account for the improvement in running temps I saw. Probably a fraction of a degree at best.

Bottom line is my oil temps dropped very significantly despite an increase in temps.

onargaroberts

I don’t know what your bearings look like. If you’re the original owner (and I believe you) then you know more about this car than anyone else in this conversation. You know if the maintenance schedule has been adhered to. You know if it has ever been overheated or if there has ever been a momentary loss of pressure in a long, sweeping corner. You have 132,000 miles giving you testimony that the lubrication system is working as designed and that the car has been reasonably well maintained. You also know if the 28 psi, hot oil, low idle (my assumptions) oil pressure is normal for this car. If it has always been 28 psi, then nothing has changed. If it used to be 48 psi (for example) and now its 28 psi, then there have been some pretty dramatic changes in the lube system (assuming the same oil). That’s worth looking into.

theVcar

Oil change 3-5k since new, rad fld 3x, rear end clutch packs 1x - fld 3x
Ps fld3-4 times, clutch fld xxx's . Very well maintained. psi was always 28-32 very hot idle.

onargaroberts

Sounds like you have a very stable car which is driven and maintained within the application scope for which is was designed. Be happy.

As a single reference data point I run M1 15W50 in my car all the time. It is not a daily driver. It gets most of it's miles in the summer time drving to and from the track. I know I have to drive easily until the oil is up to operating temperature. That's no problem for me.