Which of these for my LT-1

[cweed]

Hey guys,

I am debating trying out a new oil in my LT1. Here are my choices:

- M1 0W-40
- M1 10W-30 + 15W-50
- M1 SUV/Truck 5W-40
- GC 0W-30

I've been running M1 10W-30 in winter and M1 15W-50 in the summers, I know the engine calls for 5W-30, but the above has worked well for me, but i'd like to try some of these new oils that everyone is talking about

What do you guys recommend, especially those of you who run any of the above in your LT1's.

 

[novadude]

I know a certain member will be saying GC 10W-30.

Hi, Patman!

 

[cweed]

Yeah I know what he'll say too ;-)

He's gotten some really good results with the GC. His experience with it is pretty much the only reason I added the oil to my "try" list hehe.

 

[haley10]

I'd really like to see some of your uoa's if you've done some. Who's to say you don't already have a great solution? The 15W-50 would be especially interesting.

 

[cweed]

yeah a lot of LT1 people are against 15W-50, then there are those that use it and love it, but noone has done a UOA on it....

Sure I wouldnt run it throughout the winter, but in the summer it seems like a perfectly fine oil, never had a problem with it so i keep using it, especially since I have quite a few miles on the engine. Maybe someday I'll get myself to do a UOA on it....

I've been leaning towards trying some 0W-40 at my next oil change, maybe mixing in 1/2 1/2 with 15W-50?....

 

[Patman]

quote:

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Originally posted by novadude:
I know a certain member will be saying GC 10W-30.

Hi, Patman!

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Yep, I've had excellent oil analysis results so far with GC 0w30 in my 95 LT1 Firebird! I drive my car every day and use this oil all year round. This oil makes my engine run nice and smooth, and definitely gives better low end and midrange throttle response.

I would like to see how 15w50 M1 does in the LT1 in the summer though. So if you're running that oil now, do a UOA on it at the end of your interval.

 

[cweed]

Patman, have you tried running M1 0W-40 in your car? My change interval is coming up soon so I may actually do a uoa on my current oil. After which I'm thinking of going with 0w-40, not sure if i can find the GC stuff around me, haven't looked yet

 

[cweed]

Its the other way around here, we have plenty of M1 0W-40, but I have not seen any GC around, I'm going on a hunt this weekend though so maybe I'll find some.

I haven't seen Castrol 5W-40 either, I've only seen their 5W-50 and 10W-30 around here. I've tried Redline 10W-30 and 10W-40 and liked both, but they are a bit too pricey considering you can get M1 for almost 1/2 the price.

 

[Patman]

quote:

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Originally posted by cweed:


I haven't seen Castrol 5W-40 either, I've only seen their 5W-50 and 10W-30 around here. I've tried Redline 10W-30 and 10W-40 and liked both, but they are a bit too pricey considering you can get M1 for almost 1/2 the price.

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You raised a good point, as this is something I need to consider if I need to choose a new oil in the future. Right now I only pay $6.66 per liter for GC, but if I choose something like Redline, it's $10.39 per quart up here (and that's when it's on sale!)

But no matter what oil you choose, just make sure to choose something that is in the range of about 12cst to 14cst at 100c. So that makes it a thick 30 to low 40wt oil. The LT1 seems to really prefer this viscosity.

An oil that I think would be really good in the LT1 would be the Castrol 0w40 synthetic which is sold in Europe, Asia and Australia.

 

[cweed]

hopefully gc will stay around in your area and you wont have to make the switch. The price is what keeps me sticking with M1 so what i will most likely do is go with M1 0W-40 at next change and see how the car feels on it and do a uoa on it and compare to my current oil.

As for the Europe-only castrol 0W-40, maybe someday they'll secretly bring it over like they did with the german 0W-30...

 

[Patman]

quote:

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Originally posted by cweed:
Patman, have you tried running M1 0W-40 in your car? My change interval is coming up soon so I may actually do a uoa on my current oil. After which I'm thinking of going with 0w-40, not sure if i can find the GC stuff around me, haven't looked yet

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I have not tried M1 0w40 in my car, but I think it would do pretty well. Up here they don't sell the M1 0w40 except for in one single location in Toronto. So it's not a very convenient oil to buy. Lucky for me, GC is at all the Walmarts in my area, so I've been getting my supply from there.

If GC disappears on me, I've got a few oils I'd like to try, such as Castrol 5w40 Syntec, Mobil 1 0w40, Redline 5w30, Amsoil 5w30. All of them are more expensive alternatives though so hopefully GC is here to stay for a while.

 

[KW]

I'd give the M1 0W40 a try.

 

[formula94lt1]

what is a cst? Im coming up on an oil change interval with my scheaffers 10w 30 that I ran through winter and so far this summer, I have a previous test result of thier 15w 40 oil if you search by my member name in case your interested

 

[lococrazy]

I just tried 0w-40 in my LT1....will do a UOA but im running 0w-40 as a "year round"...

 

[ssmokn]

I know this isn't in your list of choices but I know half a dozen people (myself included) that run 15W40 oils in their LT1s with great success. I use Delvac 1300 but others I know use Delvac, Delo 400 and Fleetguard all with great success.

One of my buddies ran Fleetguard 15W40 (I was told this is repackaged Delo 400 but I don't know for sure) in his '94 Impala (LT1). He tore down the motor at 180+K for a performance rebuild. When he pulled the motor apart it was working perfectly and the internals were clean and in excellent shape.

I started out with Mobil 1 (various weights) but my LT1 never seemed to like Mobil 1. Delvac 1300 works for me and the price is right.

 

[formula94lt1]

Yeah, again I have a UOA oround here youll have to search for of the results of schaeffers 15w 40 with a K&N filter for a duration of like 4500 miles. Had great results so check it out.

 

[CheshireCat]

quote:

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Originally Posted by Patman:
But no matter what oil you choose, just make sure to choose something that is in the range of about 12cst to 14cst at 100c. So that makes it a thick 30 to low 40wt oil. The LT1 seems to really prefer this viscosity.

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Is the motor oil's cst at operating temperature the most significant factor in selecting a motor oil?
I own a 94 Z28 Convertible and I live in South Florida where the average "cold start" is around 20c-30c. My LT1 had a steady diet of M1 5w30 for the first 115k miles but I switched to M1 0w40 for the last 5k miles. I noticed in another post that at 30c the M1 0w40 has a significantly higher cst than the 5w30 at the same temp. Is this good or bad given the South Florida climate? If it matters, most of my trips are less than 3 miles.