What kind of oil does the LT1 "Like?"

[Kuma]

Hi, I've got a 96 Trans Am with the LT1, currently being upgraded to an LT4 top end. I'm wondering if anyone knows what is the "best" oil for this engine? I ran Mobil 1 5w30 for the first 5k miles or so (bought it at around 99k miles, currently 106k). Oil pressure seemed low so I went with Amsoil 5w30. Oil pressure with that is a bit better and more responsive and it seems generally smoother. However, I'm thinking of switching to either M1 or Amsoil 10w30. In fact there are 5qt jugs of the latter plus Castrol GTX and Quaker state full synth sitting on my shelf right now. Decisions, decisions...if my wife only knew how much I agonize over these things...or how much worry I've put into the fact that there's no moly in Amsoil...she would kill me.

 

[Patman]

Mobil 1 10w30/5w30 is too thin for the LT1, IMHO, I think these engines need a thicker 30wt to a lower 40wt oil. I think Amsoil 5w30 or 10w30 would be an excellent choice for the LT1, as they are thicker 30wt oils, almost 40wts really. I'm using Schaeffer Supreme 5w30 in my LT1 Formula right now, so we'll see how this interval turns out. I'm going to be doing the UOA earlier than expected, at the 3k mark (I won't drain it, I'll just sample it early) I'm really hoping this batch of Schaeffer 5w30 is closer to 12cst at 100c. Some batches of this oil are around 10cst while others are thicker (even their tech specs list a range of 10-12cst) So far all of my UOAs with their 10w30 blend showed it in the 10 to 10.3 range though, which is a bit thinner than I would like, and I think it's part of the reason my wear numbers aren't as good as they could be. This next UOA will be very crucial for me, it's my fifth interval with Schaeffer Oil, and I really hope I'm not disappointed with the numbers. I do believe it's a great oil, don't get me wrong, it just might not be the best choice for my car. We'll soon see. This is all IMHO of course, the best thing for anyone with an LT1 (or any engine for that matter) is to do a used oil analysis on what they are currently running, and go from there. Two pieces of advice though, number one, don't use a restrictive oil filter (such as Mobil 1, PureONE, Bosch Premium) and number two, don't expect good oil analysis results if you're using a K&N air filter, better to stick with OEM or a Fram air filter.

 

[9c1]

I'm currently running M1 10W30 in both my 9C1s LT1s. Engines seem content. The oil pressure gauge in the Caprices is a POS. I hope your TA is better. In a month or so (when school starts back up) I'm going to check the pressure with a real mechanical oil gauge. I am planning on going to M1 5WX for the winter, I think. I just switched to M1 (cars have 126K and 135K), so I am still accumulating experience with it. From the car gauge the M1 carries slightly higher pressure than the previous 5W30 Penz. That makes me feel a little better.

 

[Kuma]

I've got the ws6 ram air hood and am using a K&N air filter...so we shall see when I do a UOA what it looks like. Using the Delco 454 or whatever the number is now oil filter, the small one. I've heard that the SBC(?) blue air filter that SLP sells is better than K&N in that it catches more particles. Anyone have experience with that?

 

[Jim Spahr]

Best oil for an LT1 or LT4? I would listen to the Corvette engineers on this and use Mobil 1. 10w/30 for the summer and 5w/30 for the winter. After the engine has been broken in.

 

[Kuma]

I would listen to the GM engineers, however I also know that Mobil 1 paid big bucks to be the "official" corvette motor oil... After all, these are the same GM engineers that gave us the Optispark (for those who don't know, the "capless" distributor that some clever dude put right below the water pump...

 

[Patman]

Just because GM puts Mobil 1 in the Corvettes doesn't make it the best oil in the world for these engines. I can assure you that the overall quality of the oil wasn't the biggest factor in Mobil 1 getting that lucrative OEM contract. I'm not saying that Mobil 1 sucks, but there are many oils out there that are better than it. Mobil 1 could be so much better than it is, that's the saddest part. They've got the resources to make it ten times better, but then their profits would suffer. Which is why smaller oil companies can produce better oils than Mobil 1 (such as Redline, Amsoil, Schaeffer Oil, and the list goes on)

 

[buster]

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such as Redline, Amsoil, Schaeffer Oil, and the list goes on

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Give me a break, the list does't go on and on.... I agree with the first part of your response and think a heavier oil such as Amsoil would be better in a LS1/LT1 but the list is fairly short on oils that are better then M1. Molekule even agreed that M1 right now is as good as Amsoil at this particular point in time...until Amsoil upgrades with the latest from Lubrizol. [ July 29, 2003, 07:29 PM: Message edited by: buster ]

 

[Patman]

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Originally posted by buster:

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such as Redline, Amsoil, Schaeffer Oil, and the list goes on

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Give me a break, the list does't go on and on.... I agree with the first part of your response but the list is fairly short on oils that are better then M1.

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There are many oils from around the world that beat Mobil 1 too. Face it, Mobil 1 is an ok oil, but it's nowhere near the best. I'm sure it'll place last in 3MPs testing, all the other oils he is going to try will show lower wear numbers. That is something I am 95% sure of.

 

[buster]

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There are many oils from around the world that beat Mobil 1 too. Face it, Mobil 1 is an ok oil, but it's nowhere near the best. I'm sure it'll place last in 3MPs testing, all the other oils he is going to try will show lower wear numbers. That is something I am 95% sure of.

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Like what? So it's good enough for Mercedez, Aston Martin, Chevy, Mitsubhishi, but not Patman? Just kidding. I think your right, and I don't think it's the best, trust me. I don't think there is a best, it just depends on your engine etc. You might be right and if you are, I'm going with what has lower wear numbers in 3MP's study. Thats why I can't wait to see Amsoil's results. But no excuses Patman if it doesn't do well. Also, this thickness vs thinness just all depends on what engine. Bob has just layed down more evidence that in some engines, thinner is better. An oil with a good additive package and flow. [ July 29, 2003, 07:51 PM: Message edited by: buster ]

 

[Patman]

It's true, we'll never truly know what the best oil in the world is, and what works best in one engine might not work as well in another, also different driving conditions and climates play a factor too. An oil that works great in Arizona might not work as well in Alazka and vice versa. I truly believe that each engine has a specific viscosity range that it "likes" the best, it's just a matter of figuring that out. A newer Honda might like a high 20wt to low 30wt, but a looser clearance V8 probably won't. Just another good reason to do UOAs and experiment a little in order to determine your very own "holy grail"

 

[buster]

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Just another good reason to do UOAs and experiment a little in order to determine your very own "holy grail"

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I totally agree. I'm about to send off my M1 sample sometime next week or so. My Amsoil wear numbers were good. I was much harder on the M1 so I'm curious to see how well it held up.

 

[pscholte]

Patman, Wash out your mouth with ashless detergent-dispersant!!! Sure we'll find the world's greatest most perfect oil, assuming that German Castrol is not already it, of course!!! I mean we still have to try Motul 8100 E-Tech and Agip Synthetic PC and Castrol Formula R and........... [ July 29, 2003, 09:54 PM: Message edited by: pscholte ]