Oil viscosity/ oil temps

[cobragene]

Which oil would run at higher oil temps 10-30 or 20-50?

[Unique427]

Originally Posted by cobragene

Which oil would run at higher oil temps 10-30 or 20-50?

Link to Viscosity vs Oil Weight Chart.

https://motorstate.com/oilviscosity-htm/

[blykins]

There's a lot more to it than viscosity. The type of oil also matters....a lot. A synthetic oil will take a lot more oil temperature before breaking down than a regular mineral oil.

[Tommy]

Originally Posted by cobragene

Which oil would run at higher oil temps 10-30 or 20-50?

There are at least two ways to interpret this question.
1. Which weight oil performs best at a specific temperature (not named)?
2. Will the oil temperature in a controlled engine test be higher or lower than a different oil run in the same engine under the same conditions?

I don't know the answer to either.

[cobragene]

I should have been more clear. Tommy #2. I am running vr1 20-50 synthetic 6qts and my running oil temps are about 160F 1hour running in 50F ambient 2500rpm, Oil cooler is bypassed. Would the lighter oil run at a higher temp? I believe 160 is to low correct? Pressures are high enough that I could use a combo of the two oils?

[strictlypersonl]

The lighter oil will run slightly cooler, assuming the standard/synthetic ratio is equal. In a system with bearings that are properly supported by the oil film, heat is mostly generated by the energy created by the viscous (fluid) shear.

[RockBit]

When the oil temperature is 160F, what is the coolant temperature?

[cobragene]

180-190f

[bobcowan]

You are correct, 160*F is too cold. You want it closer to 200*.

Thicker oil (higher viscosity) tends to run a little hotter, as it takes more energy to move around. But it's a small difference, not enough to really matter. If the oil isn't warm enough, then look somewhere else.

How is the oil cooler bypassed? If it's an oil thermostat, then about 10% of the oil is flowing though the cooler when it's cold. As it warms up, that ratio changes. I would consider completely disconnecting the cooler.

Maybe the gauge is incorrect? Use a infrared thermometer on the oil pan to compare it to the dash gauge. They should be pretty close.

Oil is mostly heated by rpm's. If you're not road racing, there's no need (and some detriment) to using a cooler.

I'm not a big fan of 20w oil for a street engine. On cold start you want the oil to be as thin as possible, so it gets to all the important parts as quickly as possible.

The hot viscosity should be enough to maintain proper oil pressure, and that's it. it takes energy to move oil around. The thicker the oil is, the more energy it takes.

For example, in a Windsor, too thick oil can cause the distributer gear drift pin to shear. And if using a poly or bronze gear, it can wear it out a little quicker.

All my street engines us a 0W or 5W oil. Many modern street engines - like the Coyote - are designed to run on a 0W-20 oil.

https://www.racingtheexocet.com/?page_id=702

[twobjshelbys]

Originally Posted by RockBit

When the oil temperature is 160F, what is the coolant temperature?

Do you have an oil cooler?

[RockBit]

Fred Kemmerer (sp) had the same issue on ERA 753. He insulated the oil temp sender.

See the following thread.

ERA 753 - Final Assembly in Progress

[Gaz64]

Originally Posted by RockBit

When the oil temperature is 160F, what is the coolant temperature?

Originally Posted by cobragene

180-190f

With the engine at operating temperature for an hour, and the oil temp has this difference, I would think the temps of both fluids should be closer to each other. One of them is lying.
Might depend on where you are reading oil temp from. Your coolant temp sensor is up high in the coolant path. I have one car with oil temp AFTER the pump, not in the sump. The sump is where the oil is the coolest before doing the lubrication path again.

[Unique427]

You could always try slapping a few Thermax temperature strips in
critical areas to see if there is a glaring discrepancy. I have one on the
remote oil filter and oil pan. Use the "B Range" strips.

When done, they peel off with minimal effort.

https://www.thermometersite.com/ther...sible-labels-2

[cycleguy55]

Originally Posted by cobragene

I should have been more clear. Tommy #2. I am running vr1 20-50 synthetic 6qts and my running oil temps are about 160F 1hour running in 50F ambient 2500rpm, Oil cooler is bypassed. Would the lighter oil run at a higher temp? I believe 160 is to low correct? Pressures are high enough that I could use a combo of the two oils?

160°F? That begs the following:

1. How long has the engine been running before reaching that temperature?
2. What kind of load has it been subjected to before reaching 160°F? (e.g. track, highway running, stop and go driving, idling)?
3. Is the temperature stable over a period of time, an hour or more?
4. Are you sure your temperature gauge is accurate?
5. Have you validated the temperature with another device, such as another gauge or a temperature gun?

My oil temperature gauge (in the sump) typically reads 210-220°F after driving for at least 30 minutes, including highway driving - but it takes a long time to get there, as I have an 11-quart oil pan. 100% synthetic 5W30. BTW, when I ran 5W30 dino oil the temperatures were typically about 10°F higher than they are with the synthetic oil.

I run a 180°F thermostat, and coolant temperature is typically around 190-210°F, depending upon traffic, ambient temperature, etc.

[eschaider]

These coolant temps and corresponding oil temps mirror what I can reproduce in blown Modmotors. Running a coolant temp of 180˚F (engine not fully warmed up) produces an oil temp of almost exactly 20˚F less (160˚F) when the car is idling. If you do repeated aggressive acceleration events, the coolant temp can momentarily go above 190+˚F, although it is regulated to a 190˚F temperature. The corresponding oil temp will be ~170˚F, maybe 180˚F on a hot day.

Many of the internet oil temp wizard websites will tell you the oil temp should be in the 220˚F to 230˚F window. To get my oil temp that high, I need to run my coolant temp up to 240˚F (possibly higher) — which I do not feel comfortable doing. Here is an engine life expectancy table from Performance Unlimited that I saved a number of years ago — it is interesting. It argues for a 175˚F to 195˚F oil temperature for the best engine life?!?!



Additionally, because of the screw blower I use, ~240˚F coolant temps raise my in manifold IAT2, Intake Air Temperatures into gasoline's detonation danger zone, which I fastidiously attempt to avoid.

My personal preference favors Mobil-1 0W-50 oil with a 190˚F engine coolant temperature, which forces the oil temps into a cooler range than most experts today claim is optimal. I think, in the end, this comes down to personal preference. None of our engines are 100K mile operating time, candidates. The oil temperature debate appears to focus on extended component life in an operating environment (100K miles?) that we most likely do not live in and will not live in.

Use quality oil and do a Blackstone Labs oil analysis at each change. If your Blackstone Labs oil analysis comes back thumbs up, I would put the worry beads away — you're probably as good as you are going to get, or more practically can get. Time to enjoy your Attitude Adjustment Toy and forget about the experts.

[patrickt]

There is a pervasive and long-standing prejudice on the engine/car forums against sending your oil off to a lab for analysis. The participants take comfort in just blindly changing their oil as opposed to knowing what's actually in it or its condition.

[patrickt]

I think the oil in my Cobra is going on five years old now. This was the last analysis. Even the Blackstone guy told me not to change it because "old oil is better than new oil." Yep, that's right, old oil is better than new oil. See: This is Why I Don't Change My Oil