Thick Crowd

[TallPaul]

Originally Posted By: AEHaas

This example from the Red Line Oils page shows clearly that their fully synthetic single grade oils are based on the 30 or 40 or 50 grades but act as 10W-30 and 15W-40 and 15W-50 multi grade oils.
Yes,this is the case with Redline and probably some other high end oils. Reline 5w30 is both a straight 30 and a multigrade. Where the problem comes in is that I don't think base oils are necessarily specified as 5w, 10w etc. Rather, they most likely are specified by viscosity.

 

[camarolt76]

Given that straight grade oils don't have any VII, aren't they inherently superior to multigrade oils if used under the proper temperature conditions?

This has been discussed before, but what are the disadvantages to using SAE 30 during summer conditions? Cold starting is not an issue, and heat is. The Redline paper points out that viscosity at 100C is not what protects your bearings, it's HTHS performance that does that.

I will admit to being a thicker is better than thinner person. A grade thicker will not hurt an engine, but a grade thinner certainly could under stressed conditions.

 

[aquariuscsm]

Originally Posted By: camarolt76
Given that straight grade oils don't have any VII, aren't they inherently superior to multigrade oils if used under the proper temperature conditions?

This has been discussed before, but what are the disadvantages to using SAE 30 during summer conditions? Cold starting is not an issue, and heat is. The Redline paper points out that viscosity at 100C is not what protects your bearings, it's HTHS performance that does that.



I will admit to being a thicker is better than thinner person. A grade thicker will not hurt an engine, but a grade thinner certainly could under stressed conditions.


I`m a thicker oil user as well. My car`s factory FSM even recommends thicker oils (10W40-20W50) if you drive the car continuously fast and/or in warm climates(and I definitely drive my car the way a sports car is meant to be driven). Several TT Z guys have spun engine bearings while tracking their cars with a 10W30 oil.

I`m curious as you are about using straight grades instead of multi grades.......SAE40 as opposed to 15W40 during our "cool" winters here(60s and 70s),and then switching to an SAE50 as opposed to a 20W50 during our super hot summers here(100+). Oils I`ve been considering are Royal Purple SAE40 and SAE 50.

 

[Gary Allan]

How long are your typical driving events? If they're under 20 minutes, you're not at the spec'd visc anyway. If it's a straight grade ..you're at a much higher visc throughout the warm up event.

Fine for boats ...not well suited for passenger car usage outside of very few people.

 

[Taylor]

unless you warm your oil first via oil heater or idle...

in my case 20w50 is specd for the summer and 10w30 for the winter. idk about this motor(no oil temp gauge) but my 383 in my wrangler isnt "severely" affected by ambient temps where im at. at least not enough to jump 2 grades IMO. So i dont see a problem running a 0w40 year round other than the VII's. This vehicle is my g/fs and is grannied (until i get behind the wheel) It will see 120+ mph's every blue moon and 6k rpms once or twice a week. The motor only see's mid temp gauge after a long idle, other than that it sits at 3/8. Idk if thats enough to break down the VII's or not. I just worry about cold flow or lack of flow. Although its not to relavent in this motor my 4.0 jeep gets mad if it sees anything other than a 0wX. My question is do i worry to much? should i just run whats specd? or am i safe running a 5w50 or 0w40?

 

[Audi Junkie]

I don't think you have to ~worry~ about VIIs in a modern synth oil. Dino 10w-40 in sumemr and 10w-30 in winter will do you fine.

 

[Zaedock]

I use Delo 400 SAE30 in my trail Jeep in the summer. I like the 12.1cSt @100C viscosity and it's ability to hold up under long periods of the sustained RPM my 4 banger runs with the gears I have. 10W30 turns to H2O.