oil temp/pressure question

[dansmith11]

So from what I have read, oil should sit at around 100-105C is the ideal operating temp. now i just installed an oil temp gauge in my 1j supra last night, and after a few short runs (probably hitting boost like 3-4 times) my oil temps were already reading 110C. which kinda worries me considering I have a track day coming up this weekend.

now at what point is oil dangerously hot? my old 20valve 4age corolla i tracked last year would usually sit at around 110-115C under hard driving conditions, i would think that a twin turbo car where your running oil through really hot turbos, your oil temps would be higher wouldnt they?

now the problem with high oil temps is that the oil thins out to much and you lose the required oil pressure correct? so can i just watch my oil pressure guage as well, and when it starts to drop then i know my oils to hot and im losing pressure?

just trying to get a feel for when im gonna have to back off and just coast around the track and take it easy.

also im only running redline 10w30 oil, would i be better off to change it out for some heavier (5w50 perhaps?) oil to get me through this weekend? i know that running thicker oil is not the ideal solution, however being that i didnt get enough time to install my oil cooler, would running thicker oil be a good idea short term?

 

[starscream5000]

It's not the problem of the oil thinning out due to high temps that you have to worry about, it's the oil loosing it's viscosity from the heat that's the killer. You may see a slight difference between the 10W30 and 5W30, but almost every bit of that difference is going to be notice on a cold startup. You are still using a 30 weight oil, it's just going to be thinner when cold on the 5W30 than the 10W30. In other words, there's little to no difference that you will see by switching between the two of them that pertain to the oil difference when fully warmed up.

I HIGHLY recommend holding off on the race until you get that oil cooler installed, or do it first, take your time on the instal and don't rush .

 

[dansmith11]

It's not the problem of the oil thinning out due to high temps that you have to worry about, it's the oil loosing it's viscosity from the heat that's the killer. You may see a slight difference between the 10W30 and 5W30, but almost every bit of that difference is going to be notice on a cold startup. You are still using a 30 weight oil, it's just going to be thinner when cold on the 5W30 than the 10W30. In other words, there's little to no difference that you will see by switching between the two of them that pertain to the oil difference when fully warmed up.

I HIGHLY recommend holding off on the race until you get that oil cooler installed, or do it first, take your time on the instal and don't rush .

well its just a race school, not really a race/full out track day, so i know im gonna have to take it really easy , just tryin to figure out what the point is when i have to back off.

and i know going from a 10w30 to a 5w30 is only going to affect old start viscosity, im asking if its worth while to go from a 30 weight to a 50 weight for this weekend seeing as i dont have my cooler installed yet ,the 50 weight should in theory give better viscsoity at higher temps no?

 

[starscream5000]

NO. Look into the SME section under motor oils and readup on the myths of heavier weight oils .

 

[Nick M]

It's not the problem of the oil thinning out due to high temps that you have to worry about, it's the oil loosing it's viscosity from the heat that's the killer. You may see a slight difference between the 10W30 and 5W30, but almost every bit of that difference is going to be notice on a cold startup. You are still using a 30 weight oil, it's just going to be thinner when cold on the 5W30 than the 10W30. In other words, there's little to no difference that you will see by switching between the two of them that pertain to the oil difference when fully warmed up.

I HIGHLY recommend holding off on the race until you get that oil cooler installed, or do it first, take your time on the instal and don't rush .

I see you have reading comprehension skills. :biglaugh:

That is a good thing, not an insult, if only others could do the same.

 

[starscream5000]

The SME section helps out a lot! Plus jdub's patients .

 

[dansmith11]

i did read that SME section, and i understand that running heavier oil is not really the greatest solution, but he also mentions that to an extent heavier oil DOES help viscosity at higher temps, im wonder what that extent is, and if its even worth it.

i understand that the tradeoff is more engine wear under startup/warm up, but it would only be for one day and most of that day will be spent already at operating temp.

 

[starscream5000]

It's your gamble, but can you not reschedule the run for another time and get that oil cooler put on?

 

[dansmith11]

It's your gamble, but can you not reschedule the run for another time and get that oil cooler put on?

unfortunately no, its a school/licensing day thing, its mandatory to run every year before they give you your license to run the rest of the events.

ill just take it real easy and keep a close eye on my oil temp gauges, worst cause ill end up driving really slow and not pushing the car

 

[jdub]

A heavier weight oil is not the solution long term, it's also not going to harm your motor for the short term either. SS5 is basically correct...the real solution is to install a full flow, thermostat controlled oil cooler.

I'd really hate to see you dump that expensive Red Line...the good news is Red Line is an ester based oil. Same stuff used in jet turbine engines
It handles heat very well viscosity wise and resists break down from heat too. A 110 deg C oil temp on a ester oil is a piece o' cake...you will be fine using it for your event. Let the motor cool off between runs if you can.

Get your cooler installed...the 1J guys should pay attention to this

 

[suprageezer]

I also argued the thick oil view since its all I've used in every vehicle I've owned in the last 35 years. After reading Jdubs suggested site listed below I have a better and more informed view on oil Viscosity. Dr. Hass explained it better then I had ever read. Not sure if you read his Posts so take a look if not and see what you think.

http://63.240.161.99/motoroil/

 

[dansmith11]

I also argued the thick oil view since its all I've used in every vehicle I've owned in the last 35 years. After reading Jdubs suggested site listed below I have a better and more informed view on oil Viscosity. Dr. Hass explained it better then I had ever read. Not sure if you read his Posts so take a look if not and see what you think.

http://63.240.161.99/motoroil/

so i read all that, he talks about oil pressure vs. flow , is there any way to figure out what a particular enignes flow characteristic would be? any forumla or calculations to figure it out based on oil pressure and visocity? or would i have to ask the guys who engineered the 1jz? lol

 

[jdub]

What you're looking for is 10 psi per 1000 rpm...you can't have "too much" flow IMO. Don't confuse (or equate) flow with pressure...psi is the "carrier", flow is volume.

To get more precise, you would need to know the dimensions of every oil channel/pipe in the motor, the capacity of the pump, and the flow characteristics of the filter. Even then, it would not be completely accurate. The above rule of thumb works quite well across almost all of the motors out there.

 

[dansmith11]

What you're looking for is 10 psi per 1000 rpm...you can't have "too much" flow IMO. Don't confuse (or equate) flow with pressure...psi is the "carrier", flow is volume.

To get more precise, you would need to know the dimensions of every oil channel/pipe in the motor, the capacity of the pump, and the flow characteristics of the filter. Even then, it would not be completely accurate. The above rule of thumb works quite well across almost all of the motors out there.

so assuming i still have 10 psi per 1000rpm, i should be good even if my oil temps get above 110C? ie. say my oil temps get to 120-130 (just hypothetical), but i still have 10psi per 1000, am i still good for lubrication? or is there more to it then that and at a certain point the oil is not doing its job even if there is still 10psi per1000 ?

in those articles he talks about oil in racing conditions reaching 300F which is like 150C, im thinking even an ester based oil like redline at 10w30 is proably not gonna cut it at 150C

 

[dansmith11]

so for furture reference (if anyone cares)

a 1jz is good for about 2-3 laps (approx 3-5 minutes) of hard driving before oil temps reach 120C.

so if your going to do any hard driving , go buy an oil cooler.

and this was on a day where it was only about +8-10 C, in the afternoon when the air temps got up to over +20 C, i could barely run one lap before having to back off due to oil getting too hot.

 

[starscream5000]

Keep us updated on the oil cooler install.

 

[jdub]

so assuming i still have 10 psi per 1000rpm, i should be good even if my oil temps get above 110C? ie. say my oil temps get to 120-130 (just hypothetical), but i still have 10psi per 1000, am i still good for lubrication? or is there more to it then that and at a certain point the oil is not doing its job even if there is still 10psi per1000 ?

in those articles he talks about oil in racing conditions reaching 300F which is like 150C, im thinking even an ester based oil like redline at 10w30 is proably not gonna cut it at 150C

Most syn oils will handle those temps easily short term...especially an ester based oil like Red Line. However, you want the oil as close to 100 deg C as possible...this is the "right" temp for the oil and yields the viscosity (10-11 cst) the bearings were designed to operate at. Running any oil in the 120-150 deg C range for extended periods is shortening it's ability to perform as specified.

Using a heavy weight oil to compensate for high oil temps is a double edge sword in a couple of ways. You have to get the oil to the temp that will yield the "right" viscosity...cold flow will suffer as a result due to viscosity being 2-3 time what you see with a 10W-30 cold. Higher temps are not good for your bearings...those too were designed for the 100 deg C range...higher temps = increased bearing wear or even failure.

The correct solution is to use a cooler with the thermal capacity to keep the oil at the "right" temp. The thermostat it there to warm the oil up as quickly as possibe to that temp and then modulate flow to keep it there.

 

[dansmith11]

ok so i installed my cooler, and my oil pressure seems to have gone up quite a bit, i seem to have way to much oil pressure now

originally i just installed a sandwhich plate with my oil temp and pressure guages in it. now i relocated my oil filter as well as ran an inline thermstat and an oil cooler. so im still using the sandwhich plate, it goes sandwich plate -> filter relocation adapater -> filter -> t-stat -> from t-stat 1 line back to the engine and 2 off to the oil cooler, oil is directed back to the enigne when cold and forced to the cooler when hot.

before i would have 30-35psi oil pressure at idle and 70-80ish at around 5-6k rpm

now im sitting at 55psi at idle, and just reving the car up a bit to say 4k rpm im hitting like 105 psi, is this not excessive? i dont see how adding an oil cooler would increase oil pressure.

could it just be an issue with where my gauge is mounted? i've been told that putting a pressure gauge in a sandwhich plate at your filter isnt the best place for it and you dont see full/accurate pressure readings. so the only thing i can think of is my oil pressure was always this high but i wasnt seeing full readings before because my gauge is located in a place where the oil is about to enter the filter and theres less pressure there, and now theres full flow past this point so im getting the accurate readings?

assuming this is accurate though, isnt 100psi just reving the engine with no load on it excessive?

 

[starscream5000]

I would get rid of the sandwich plate and get the adaptor that needs the NA stud the screw in -> Filter relocation adaptor -> filter -> t-stat -> Line in to oil cooler -> oil cooler -> line out back to t-stat -> line from t-stat going back to adaptor plate.

I would also put your oil pressure gauge where you stocker is, you'll need to correct adaptor for that one too.

 

[bwest]

sandwich plate = adapter on the block, won't have an effect on actual oil pressure except:
you are reading the pressure at the pump outlet. Not what the motor sees (has to pass through the cooler set-up. Ever blown through a straw?). I think a more accurate way to see 'real' pressure would be to measure it at the block (like SS5 mentioned).

There are 2 other places on the oil rail that you can use for an oil pressure gauge (w/o removing the stock one). both use 1/8 BSPT fittings (not NPT!!). Leave the stock gauge.