Forced Induction Oil Viscosity
 

Just wondering what oil viscosity everyone is using with forced induction?


I am using Fully Synthetic Nulon 5w-30 and had previously ran royal purple 10w-40 (tuners recomendation).


After talking with a few others they where using 5w-30 so i decided to give it a try after getting the shits about not being able to find anywhere local that had royal purple 10w-40 instock.


I got to thinking about it and thought that 10w-40 was a big jump from the recommended 0w-20 in stock NA. The car is mainly a daily with a few spirited drives.



So far i noticed the car is a bit more lively down low but was interested in what everyone else was doing.

I stuck with the oem 0w-20 when I had my Edelbrock SC installed and never had a problem. Car was my daily, did regular.canyon/backroad driving on the weekends and was tracked 6-10 times a year. Only thing I added was an oil cooler for those 100+F (38 C) trackdays.

Thanks for the info. I take supercharger isn't oil cooled though?



Im running a 3072 water and oil cooled garret. I was a little worried about cooking 0w-20 in the turbo. Spirited driving (not track) can see oil temperatures of 115 degrees with 0w-40 at very low ambient temperatures (only had FI over the last four months spirited driving has been at sub 20 degrees). I live in western Sydney so in summer get regular 40 degree days.



Im on the stock oil cooler so maybe its worth a look into.


While it could be a pleasebo effect the car feels a lot more lively with 5w-30 then 10w-40. Not sure id go back.

Some highlights from..

https://www.google.com/amp/s/540ratb...t-ranking/amp/

To provide an engine with the best “oil film strength/load carrying capability/shear resistance” wear protection during cold startup and normal operating temperatures – Select a HIGHLY RANKED motor oil from my Wear Protection Ranking List, that has the lowest cold viscosity rating, AND that also has the lowest hot viscosity rating, that will still maintain acceptable “HOT” oil pressure. For properly built engines, a highly ranked 5W30, will usually fulfill those requirements.

NOTE: When I talk about using thinner oil in engines as long as the oil pressure is still acceptable, I am generally referring to gas engines in Hotrods and Race cars, where any thoughts of referring a factory stock engine and its Owner’s Manual, has gone out the window, and where people tend to want to use 20W50 because they MISTAKENLY think it might be better. For those engines, there can be a significant improvement in oiling by using thinner oil than 20W50, as long as the oil pressure is still good. I say that, because a lot of those engines weren’t built with a high volume oil pump, and thin oil with a standard volume oil pump, can be asking for trouble. Thus, my comment about still needing acceptable oil pressure, in order to safely run thin oil in those engines.
But, virtually all newer gas engine vehicles now call for thin oils from the factory. So, they are already in good shape regarding motor oil viscosity.
Typical main bearing oil temps can be 55*-90*F higher than sump temps. However, main bearing oil under running conditions is not just a film of oil, it is a liquid wedge of flowing oil (that is why the cooling benefits of better flowing thinner oil are important here to avoid driving up bearing temps.
high detergent levels, and heavy viscosities did NOT play any particular roll in how well a motor oil does or does not provide wear protection. The only thing that matters is the base oil and its additive package “as a whole”, with the primary emphasis being on the additive package, since the additive package is what contains the extreme pressure anti-wear components.
VISCOSITY COMPARISON:
20 wt oils rank between number 2 and 198.
.
30 wt oils rank between number 1 and 209.
.
40 wt oils rank between number 5 and 197.
.
50 wt oils rank between number 37 and 206.
.
So, as you can see, oil viscosity plays no particular role in an oil’s wear protection capability. As mentioned above, an oil’s wear protection capability is determined by its base oil and its additive package “as a whole”, with the primary emphasis on the additive package, which contains the extreme pressure anti-wear components, which has nothing to do with viscosity.
Notice that cold 5W20 at 51.6 cSt, is 2.6 times THICKER, than hot 20W50 at 20.2 cSt. Now you know that a low viscosity cold rating does NOT mean the oil is thin when it’s cold.
Oil flow is also what carries heat away from internal engine components. Those engine components are DIRECTLY oil cooled, but only INdirectly water cooled. And better flowing thinner oil will keep critical engine components cooler because it carries heat away faster than slower flowing thicker oil can. This is especially important with plain main and rod bearings, since the flow of oil through the bearings is what cools them. If you run thicker oil than needed, you will needlessly drive up engine component temps.
Almost no engine should ever need to run oil thicker than a multi-viscosity 30 weight. The lower the hot viscosity rating, the number after the W, the better the hot flow. For example, hot 5W30 flows WAY better than hot 10W60. Thinner oil will also typically increase HP because of less viscous drag and reduced pumping losses, compared to thicker oils.
Thinner oil will also drain quicker back to the sump, to help keep the oil level high enough to prevent the oil pump pickup from sucking air during hard braking or cornering.*




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Thanks for that very helpful. I did some reading up as well on Bob is the oil guy. Made me realise how many misconceptions there are out there and many people are running thicker oil under false pretenses.

The oil debate again.
I have no answers to my gt86 questions but I will make a point as an owner operator of several aircraft over 50 years.
All engines are boxer style hor opposed.
I run multi grade shell aero in winter for easier cranking and starting.
I run aero 100 d in summer.

Oil pressures get high in winter at start near 100 psi so not wanting to lose my oil cooler
I change oil every fifty hours or six months and use multi grade in winter.
My engine is a turbo charged six 300 horsepower.
Run 45 inches of manifold boost at takeoff but only for five minutes
And we only pull 2500 rpm.
But in summer engines get really hot as they are air cooled.
Usually go bang on takeoff.
Real important to idle down on landing to get egt down and cool turbo.
Oil temps run from 100 to 300 F on the dial
Pressures 75 to 100 psi.
Super refined aero oil is only $7 per litre compared with rip off 0-20 at $15
Never had an engine fail in 6500 hours of flying. 650000 nmiles 1.5 million km.

Its really interesting to watch the oil pressure and water temp on a cat twin turbo diesel running as an emergency power plant.
On full load 500 kw water is 82c and pressure 150 psi.
As soon as load sheds the engine goes into 8 minute cool down cycle watervdrops to 70c and oil pressure goes up to 200 psi.
We change EPP oil when the chemical analysis shows the ph has changed and engine alloys are present.
These are million dollar engines that come on line in 20 seconds.

I always remember the coroners fundings of the chieftain crash at
Portland in 1981.
Racing off to take off without warming and testing engines at full boost prior to take off, and after landing shutting engines down immediately allowing turbos to rattle down with no oil.
Engine pre take off check full manifold run up and oil in the green.

Thats why people use turbo timers folks. .



Surprised there is no oil pressure gauge and just a light in a $30000 racing rocket.

Haha . . that light on our rockets are dummies , they go off at about 4psi from memory ;)

I have a Harrop supercharger and I'm still using 0W-20, specifically Penrite Enviro+.

I inquired with Harrop directly and asked them if the stock weight oil was appropriate, and they indicated that for most applications it was.