Rotella T4 15w40 + Lucas in a 93 Corvette Autocross Race Car

[Vermess]

You're over thinking this, brother.

You're running a LT1 that's probably not even outputting 1hp per cube. That combo running AX just needs some Mobil1 40 grade, thermostatic oil cooler and a oil temp gauge. You're worried about the wrong thing. I'd worry more about that "lightweight " flywheel. Bad combo for AX.

 

[RooflessVW]

It’s expensive, shears terribly (T4 does) and mostly just marketing.

Lots of better engine oils out there for HDMO use, for the same or less money.

They spend 55-60 million a year marketing Rotella. Someone is paying for that…

Shears terribly in what? By what means? There may be better HDEOs out here, but what would make Rotella inadequate for this SBC?

Every one advertises and I don't see how that's relevant here.

I would also not run a LL euro oil - too much detergent.

What?

 

[RooflessVW]

The only real suggestion I have to the OP is to check out different brake pads. Powerstop pads are just ok.

 

[Robvette]

I'd worry more about that "lightweight " flywheel. Bad combo for AX.

The flywheel was specifically installed for AX. Better burst accelerations, quick rev matching.

This car will definitely see some track days too, it only will come out on nice, warm to hot days, there are no downsides to M1 15w50.

M1 15w50 is only $27 w free shipping. https://a.co/d/ejmpyke so it's actually less expensive than Rotella + Lucas.

 

[userfriendly]

Why a diesel oil at all? Why not just run Mobil 1 HM in 5W-30 or 10W-40? Or if the car is catless and some extra zinc is desired, then Valvoline VR1.

I'm very weary of diesel oils in gas applications. Gasoline oils contain more anti-foamer to match the general higher redline of gas engines, and I'm not sure why people would want to roll the dice on that.

Why a HD oil at all in performance applications? Because they work, are readily available and relatively inexpensive.
Btw, the anti foam additive argument against HDs is getting old. I guess it’s just another talking point that gets repeated until it becomes fact.

 

[cheesepuffs2]

Why a HD oil at all in performance applications? Because they work, are readily available and relatively inexpensive.
Btw, the anti foam additive argument against HDs is getting old. I guess it’s just another talking point that gets repeated until it becomes fact.

This is hardly a performance application though which is why this whole thread and debate is silly to begin with. We're talking about a basically stock LT1 here on an autox course. There is no special need here. He could run something even like regular Valvoline white bottle in the specified weight on the fill cap and it would be totally fine.

 

[TiGeo]

This is hardly a performance application though which is why this whole thread and debate is silly to begin with. We're talking about a basically stock LT1 here on an autox course. There is no special need here. He could run something even like regular Valvoline white bottle in the specified weight on the fill cap and it would be totally fine.

This.

 

[Robvette]

This is hardly a performance application though which is why this whole thread and debate is silly to begin with. We're talking about a basically stock LT1 here on an autox course. There is no special need here. He could run something even like regular Valvoline white bottle in the specified weight on the fill cap and it would be totally fine.

The 5w30 factory fill was prescribed to meet CAFE fleet fuel economy targets. Not to protect a 30 year old engine being run at WOT, over and over and over. In AX it'll rarely be shifted into 3rd, but it will go WOT to near the redline repeatedly.

Your recommendation is valid for a commuter vehicle that occasionally enjoys a spirited acceleration onto a freeway. But even then, if it's a 30 year old engine, moving up at least one viscosity grade is advisable.

 

[cheesepuffs2]

The 5w30 factory fill was prescribed to meet CAFE fleet fuel economy targets. Not to protect a 30 year old engine being run at WOT, over and over and over. In AX it'll rarely be shifted into 3rd, but it will go WOT to near the redline repeatedly.

Your recommendation is valid for a commuter vehicle that occasionally enjoys a spirited acceleration onto a freeway. But even then, if it's a 30 year old engine, moving up at least on viscosity grade is advisable.

Oh my goodness, I didn't even read the whole post, I stopped after "WOT over and over".

This engine has zero issues being taken to WOT, even over and over and over. It is a very understressed application that we're talking about, where the engine will go WOT for spurts over about a one minute run a handful of times per autocross day. Any current oil off the shelf at Walmart will work flawlessly for this application. Autocross isn't some boogeyman that's going to destroy the oil.

Also, earlier in the thread I did call for Mobil 1 HM in either 5W-30 or 10W-40. My point is that you're way over-thinking this and also putting too much stock into the "racecar" aspect. It's a stock engine with stock tuning approaching the stock redline.

 

[Foxtrot08]

Shears terribly in what? By what means? There may be better HDEOs out here, but what would make Rotella inadequate for this SBC?

Every one advertises and I don't see how that's relevant here.

There’s other options that are better for similar prices. When it comes to 15w40’s you can buy a number of others products that perform better and cost less.

I wasn’t tagged in the original post about a SBC. Honestly, it doesn’t matter. Run 15w40, run redline, run HPL, run whatever floats your boat.

But in Rotella’s primary market, it shears. Right around the 300-350 hour mark, especially in stationary engine applications.

Rotell spends basically, more than the rest of the entire engine oil market does, combined, on advertising. It’s mentioned because advertising makes people think it’s some super amazing product. That’s all.

 

[kschachn]

But in Rotella’s primary market, it shears. Right around the 300-350 hour mark, especially in stationary engine applications.

Are they using an inferior VII?

 

[TiGeo]

The 5w30 factory fill was prescribed to meet CAFE fleet fuel economy targets. Not to protect a 30 year old engine being run at WOT, over and over and over. In AX it'll rarely be shifted into 3rd, but it will go WOT to near the redline repeatedly.

Your recommendation is valid for a commuter vehicle that occasionally enjoys a spirited acceleration onto a freeway. But even then, if it's a 30 year old engine, moving up at least one viscosity grade is advisable.

M1 5W30 is plenty for this car in this use and is hardly "Cafe thin".

 

[RooflessVW]

The 5w30 factory fill was prescribed to meet CAFE fleet fuel economy targets. Not to protect a 30 year old engine being run at WOT, over and over and over. In AX it'll rarely be shifted into 3rd, but it will go WOT to near the redline repeatedly.

Your recommendation is valid for a commuter vehicle that occasionally enjoys a spirited acceleration onto a freeway. But even then, if it's a 30 year old engine, moving up at least one viscosity grade is advisable.

Don't let these guys give you too much ****. A 40 or 50 grade oil is not a bad choice.

 

[Vermess]

The flywheel was specifically installed for AX. Better burst accelerations, quick rev matching.

Better acceleration, I'll give you that. Off the line, yes....how much a difference, maybe negligible. Quicker Rev match??? I've found exactly the opposite. Depending on gearing, a heavier flywheel will actually help with Rev matching and keep the engine in a sweeter spot due to retained inertia.

For a road course car, depending on the track, absolutely I'd go with a lighter flywheel.

 

[Vermess]

The 5w30 factory fill was prescribed to meet CAFE fleet fuel economy targets. Not to protect a 30 year old engine being run at WOT, over and over and over. In AX it'll rarely be shifted into 3rd, but it will go WOT to near the redline repeatedly.

Your recommendation is valid for a commuter vehicle that occasionally enjoys a spirited acceleration onto a freeway. But even then, if it's a 30 year old engine, moving up at least one viscosity grade is advisable.

I highly doubt that CAFE was as influential in the early 90s as it is today. Even today's standards, GM specs 40 grade.

It seems you got it all figured out, why ask and dismiss his answer so quickly???

Or is this a ErMyGeEeEErrrrd look at my "racecar" attention thread????

You j7st got the car. Change the oil to a grade these gentlemen have recommended, run it first, watch your oil Temps, then make a final decision. Start with mobil1 40 grade. Report back.

 

[cheesepuffs2]

I highly doubt that CAFE was as influential in the early 90s as it is today. Even today's standards, GM specs 40 grade.

It seems you got it all figured out, why ask and dismiss his answer so quickly???

Or is this a ErMyGeEeEErrrrd look at my "racecar" attention thread????

You j7st got the car. Change the oil to a grade these gentlemen have recommended, run it first, watch your oil Temps, then make a final decision. Start with mobil1 40 grade. Report back.

Agree with all of this, and I'll add that more so than deciding which oil to run next, I'd be more concerned about the past history. A steady diet of mediocre oil diluted with goop would have me wondering about the condition of the cam lobes. The choice of which oil to use next is basically a brainless one, but coming from the T4/Lucas combo, that's a bigger question mark in my opinion than anything else.

Out of curiosity OP, which oil has been used on the transmission and rear diff?

 

[Robvette]

Agree with all of this, and I'll add that more so than deciding which oil to run next, I'd be more concerned about the past history. A steady diet of mediocre oil diluted with goop would have me wondering about the condition of the cam lobes. The choice of which oil to use next is basically a brainless one, but coming from the T4/Lucas combo, that's a bigger question mark in my opinion than anything else.

Out of curiosity OP, which oil has been used on the transmission and rear diff?

GM syncromesh fluid for the trans and GM diff fluid w the diff additive.

@Vermess in my original post I wasn’t asking a question. I agree M1 HM 10w40 would be a fine choice too. And, I’m confident 15w50 will excellent too.

I was just sharing this T4/Lucas anecdotal info because I think it’s interesting and the BITOG community would too. The past owner has been racing and wrenching motorcycles and cars for 35 years. He’s used Rotella in everything. Rotella has a cult-like following.

I doubt these guys are doing UOAs but if they were experiencing premature engine issues or even more repairs needed more often than their competitors, that might come out during a 35 year career. Or maybe not.

This car had 3 owners before me. The original owner for 14 years, the next owner for another 14 years and the guy I purchased it from bought it last September.

The prior owner did say he overfills the oil by a quart too. This is actually a really common practice in cars being track or autox raced so there are no oil starvation issues in high G cornering.

Fwiw CAFE has been around since the 70s and it’s the cause of Corvettes having such low power and from the mid 70s thru the later C4s. If you don’t believe that low oil weights were then and are now are a fuel economy strategy - that’s totally fine. Run whatever you’d like in your cars.

I agree that there are plenty of 10w40 and some 5w50 oils that would be good in this Corvette too. Loads of folks were putting 10w40 oils in these cars when new. After 30 years and 127k miles I’m not putting a 30 weight in it.

Now our 2024 Subaru OBW calls for a 0w20 and I will be putting a 5w30 synthetic in it starting with oil change #1

 

[cheesepuffs2]

@Robvette I believe you're confusing CAFE with the Clean Air Act, which mandated catalyic converters. That is what killed power outputs at that time.

As for the previous owner of your car overfilling by a quart to prevent oil starvation at high Gs during autocross, yikes. Overfilling can cause whipping/foaming of the oil. Oil starvation issues are rare during HPDEs, let alone during autocross where there are no long, sustained corners where there would actually be time for the oil to pack over into one side of the sump away from the pickup anyway. I would advise against continuing that practice.

I would also advise you that just because somebody has been wrenching for 35 years doesn't necessarily mean they've been wrenching well.

 

[Brian123]

Mobil 1 15W-50 has a HTHS Number of 4.5, I did not know that!

 

[ka9mnx]

Didn't GM move to xw-40 for this application?