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What weight oil do you guys like for the LT1?

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Old 08-21-2011, 07:05 PM   #1
Sworn
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Default What weight oil do you guys like for the LT1?

What weight oil do you guys run in your LT1 motors? I think they recommend Mobil 1 5W30. In my opinion Mobil 1 5W30 is a bit thin. Any ideas? Thanks
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Old 08-21-2011, 07:07 PM   #2
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Your opinion and the factory recommend oil weight are two totally different things. I use what the factory recommends.
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Old 08-21-2011, 07:16 PM   #3
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Your opinion and the factory recommend oil weight are two totally different things
I understand that, thank you.
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Old 08-21-2011, 07:17 PM   #4
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There is no 'weight' classification, as such, for oil. More correctly, it is classified as 'grade'. Of course, the nomenclature of weight seems to persist everywhere. The only mobile one oil that has any protective ZDDP anymore is 15-50 and that may change any day. The oil companies figure that most modern vehicles now have rollers lifters and do not need as much ZDDP which is harmful to catalytic convertors. Personally, I go with AMsoil in order to have better protection for start up and high RPM acceleration. That's pretty much it in a nutshell......
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Old 08-21-2011, 07:20 PM   #5
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There is no 'weight' classification, as such, for oil. More correctly, it is classified as 'grade'. Of course, the nomenclature of weight seems to persist everywhere. The only mobile one oil that has any protective ZDDP anymore is 15-50 and that may change any day. The oil companies figure that most modern vehicles now have rollers lifters and do not need as much ZDDP which is harmful to catalytic convertors. Personally, I go with AMsoil in order to have better protection for start up and high RPM acceleration. That's pretty much it in a nutshell......
Thank you for the response. I've heard nothing but good things about Amsoil.
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Old 08-21-2011, 07:25 PM   #6
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Originally Posted by Sworn View Post
I understand that, thank you.
Sorry if I was a little harsh with that answer, I've read so many oil threads. The LT1 came from the factory with pretty tight clearances which doesn't need a higher viscocity oil. I have used Mobil 5w30 for most of my oil changes. I tried Mobil 1 0w30 a couple of times, it's still a 30 weight oil. I even tried 0w40 for a brief period. But, for a stock LT1 with all things considered including price and availability you can't beat Mobil 1 5w30.
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Old 08-21-2011, 07:40 PM   #7
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Sorry if I was a little harsh with that answer, I've read so many oil threads. The LT1 came from the factory with pretty tight clearances which doesn't need a higher viscocity oil. I have used Mobil 5w30 for most of my oil changes. I tried Mobil 1 0w30 a couple of times, it's still a 30 weight oil. I even tried 0w40 for a brief period. But, for a stock LT1 with all things considered including price and availability you can't beat Mobil 1 5w30.
No worries and thank you for the clarification.

A few years ago I had a 95 LT1 Trans Am. I did some experimenting with different oil weights/grades. The oil pressure definitely improved with a thicker oil. I started a thread about it on another forum, maybe lS1 tech.....

A few people seemed to agree and advise that Mobil 1 5W30 is a bit on the thin side. Ever since then I've been a bit apprehensive about 5W30.
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Old 08-21-2011, 07:41 PM   #8
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I always put in the Factory fill Mobil 1 5W 30
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Old 08-21-2011, 08:01 PM   #9
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I use Mobil 1 5w30 in both the vette and the turbo volvo....and with a quarter million miles between the two and neither burn a drop of oil between changes I think I will stick with it.
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Old 08-23-2011, 07:32 PM   #10
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stay with the recommended viscosity. If you lived in south where the ambient temps are high I would move to the 40 weight.
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Old 08-23-2011, 07:52 PM   #11
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Quote:
Originally Posted by RLG View Post
stay with the recommended viscosity. If you lived in south where the ambient temps are high I would move to the 40 weight.
His location says Chicago. So, he's not in the tropics. Thinner is better for several reasons. Better fuel economy, better lubrication at the critical start-up phase, and adds more HP. You're better off with 5-30 at least 9 months out of the year.

The only reason you to consider thicker oil is to address blow-by issues. BTW...It seems like that would be the only time significant oil would make it to the converter. Are they really worried about zinc burning out converters in engines headed downhill?
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Old 08-23-2011, 08:07 PM   #12
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Originally Posted by Sworn View Post
No worries and thank you for the clarification.

A few years ago I had a 95 LT1 Trans Am. I did some experimenting with different oil weights/grades. The oil pressure definitely improved with a thicker oil. I started a thread about it on another forum, maybe lS1 tech.....

A few people seemed to agree and advise that Mobil 1 5W30 is a bit on the thin side. Ever since then I've been a bit apprehensive about 5W30.
so what are the down sides with using a thicker oil? how about less oil flow.....
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Old 08-23-2011, 08:14 PM   #13
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If your engine is in good condition continue to use 5w-30. That's what I use and I'm 800 + miles further south.
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Old 08-23-2011, 10:22 PM   #14
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I'll have to look in the garage and see what I bought for mine.
Wife has an 04, one car calls for 10w30, the other calls for 5w30 so I always get confused until I go in the garage and count the cases. More cases = my car oil.
Love those Costco coupons, last time we got 6 cases. 4 for mine and two for hers.
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Old 08-24-2011, 06:47 AM   #15
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Quote:
Originally Posted by Sworn View Post
What weight oil do you guys run in your LT1 motors? I think they recommend Mobil 1 5W30. In my opinion Mobil 1 5W30 is a bit thin. Any ideas? Thanks
no flames, but can i ask, why do you think that, and what weight do you think would be better - 10W40, 20W50, ??? if your engine is in good mechanical condition and without issues, you should use the factory recommended weight, or grade, for normal driving. heavier weight oil does not necessarily posses better lubricating properties. if you change your oil at, or before the recommended intervals, use a premium filter, and take proper care of your car, i'd say you could probably get over 300K out of that LT1. you won't find one person that blew his engine, or just plain wore it out, because of using 5W30. FWIW, i use the recommended 5W30 mobile1 in my 96.

Last edited by Joe C; 08-24-2011 at 07:02 AM.
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Old 08-24-2011, 04:21 PM   #16
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no flames, but can i ask, why do you think that, and what weight do you think would be better
No prob, as I mentioned above, I noticed a decrease in oil pressure on my old 95 LT1 Trans AM with Mobil 1 5W30. I believe it came with 10W30 when I purchased it.

Although consensus on the board seems to be a 5W30 weight/grade. That being said, I'm strongly leaning towards Amsoil 5W30 with maybe a K&N filter.
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Old 08-24-2011, 04:29 PM   #17
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Ive been using 10W30 since 1997.

This day I had 10W30 and all worked fine.

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