Brad Penn 40W

[usraptor]

Mobil 1 synthetic 15W-50 is made for flat tappet cams (read the label) and will provide better lubrication at start up than straight 40W.   Several studies have determined that the majority of engine wear, under normal conditions, occurs at engine start and warm up due to inadequate lubrication.   That and closer engine tolerance are why virtually all major engine manufactures/car companies now recommend 5W-30 in their engines and in some cases 0W-30.

I've also read that Valvoline Racing oil works well with flat tappet cams.  Personally, I'm running Hemmings 20w-50 in my 440/512 stroker.

[RUNCHARGER]

Yes: Startup is exactly why I never run single weight oil. Also it doesn't matter how hot it is where you live, hot engine temperature is controlled by the thermostat.

[dodj]

I'm just wondering why anybody would prefer a 15w or 20w in a mutli viscosity oil when you can obtain 5W40 or 5w50. If you want or need the 40 or 50 weight at running temps, ok, but why not get the advantages of the 5W rating for start-up?

I'm not asking cuz I'm an oil wizard or anything, just trying to learn.

[cudabob496]

I'm just wondering why anybody would prefer a 15w or 20w in a mutli viscosity oil when you can obtain 5W40 or 5w50. If you want or need the 40 or 50 weight at running temps, ok, but why not get the advantages of the 5W rating for start-up?

I'm not asking cuz I'm an oil wizard or anything, just trying to learn.

yes, want low viscosity at startup. Oil takes a little while to get to all places after startup, especially the
valve train. And 5W synthetic flows quicker than 5W regular oil, due to its shear properties I suspect.

[RUNCHARGER]

My Viper calls for 0-40. Vipers aren't driven in -40 (no snow tires available in 345 I suppose).

[cudabob496]

pushing 40 or 50wt around robs horsepower

https://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=201805


3% diff on my car would be about 18 hp

[Jim AAR]

pushing 40 or 50wt around robs horsepower

https://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=201805


3% diff on my car would be about 18 hp

Yeah but his testing was done on Motorcycle Engines and the HP difference would make sense. Motorcycle engines have a power band between 5000 and 10000 rpm so the tolerances have to be tighter (otherwise you would never be able to rev it that high) and that explains why using thinner oil makes more horsepower on Motorcycle engines.

Car Engines have power bands between 3000 and 7000 rpm approximately, if you look at dyno tests the horsepower will bottom out at a certain point and just because you rev it more does not always mean that it will keep producing more horsepower. Car engine tolerances are not nearly as tight as on Motorcycle engines.

Bottom line is that the tighter your clearances are (especially crank clearances) the thinner oil you can use.

Too me, the marginal horsepower you will gain on a Car Engine (unless it's a full blown race engine) just is not worth it. The last thing you want to do is spin a bearing and blow a rod through your block for maybe a 3% gain in horsepower.

Here's a good article on race engines explaining that: http://www.dragracingscene.com/tech-content/is-thinner-oil-better/

[cudabob496]

some good info. But running 5-30w full synthetic
on my 496 for 15 yrs seems to be working fine, and the
motor cylinder pressures were just checked last month
and all were 190 psi. Do you think I'm risking something by
using the 5-30w?

[RUNCHARGER]

Nope: You're doing well obviously.

[dodj]

Valvoline says not to use their VR1 racing oil in a street car.  You need to change out VR1 frequently. It's not meant to be in an engine for long miles.
But with the miles we probably put on our ebodies between changes, it's probably just fine, as JimAAR seems to prove out.

From Valvoline site:
"The Valvoline VR1 Racing and other racing oils not intended for passenger vehicles"


The fewer detergents/additives which protect against corrosion seems to be the difference? Without the stop and go of a street car, a racing engine doesn't build up the moisture, so it doesn't need the additives that combat the condition.

[cudabob496]

Valvoline says not to use their VR1 racing oil in a street car.  You need to change out VR1 frequently. It's not meant to be in an engine for long miles.
But with the miles we probably put on our ebodies between changes, it's probably just fine, as JimAAR seems to prove out.

From Valvoline site:
"The Valvoline VR1 Racing and other racing oils not intended for passenger vehicles"
The fewer detergents/additives which protect against corrosion seems to be the difference? Without the stop and go of a street car, a racing engine doesn't build up the moisture, so it doesn't need the additives that combat the condition.

wonder how VR1 racing oil is better than Mobil 1 full synthetic ?

[Jim AAR]

Valvoline says not to use their VR1 racing oil in a street car.  You need to change out VR1 frequently. It's not meant to be in an engine for long miles.
But with the miles we probably put on our ebodies between changes, it's probably just fine, as JimAAR seems to prove out.

From Valvoline site:
"The Valvoline VR1 Racing and other racing oils not intended for passenger vehicles"
The fewer detergents/additives which protect against corrosion seems to be the difference? Without the stop and go of a street car, a racing engine doesn't build up the moisture, so it doesn't need the additives that combat the condition.

wonder how VR1 racing oil is better than Mobil 1 full synthetic ?

But then they also go on to say a little lower in the article the following:

What solutions does Valvoline offer to the zinc issue?
Valvoline offers two solutions to the zinc issue:

Valvoline VR1 Racing Oil: Contains 75% higher zinc than SN or SM motor oil with a balanced additive package designed to work in both racing and traditional applications. Valvoline provides this product in both multi and mono viscosity grades: 20w50, straight 50, 10w30, straight 30, straight 40 and straight 60.

I rarely put on more than 1000 miles between changes as I rarely drive long distances in it so it would never build up enough contaminants or moisture to affect it, besides if I drove it long distances,I would need to take a loan to pay for the gas at today's prices. LOL

[Michael_B767_ATP]

Hi Everyone,

Just found this in a service manual.


Thanks Everyone
Mike

[cudabob496]

Hi Everyone,

Just found this in a service manual.


Thanks Everyone
Mike

I think that recommendation of heavy oil for performance engines is old school/out-dated.
650 hp Vettes coming out of the factory use 5w-30 Mobil I full synthetic.

[cordodge]

I run Joe Gibbs LS-5/30 in my 572 Hemi as Tim Banning's (forhemisonly)advised, He was very firm on that so I'm not about to question him for sure.

Bruce.