Oil
Racer
Joined: Jan 2012
Posts: 398
Likes: 22
From: Las Vegas NV
5w-30 and 10w-30 are the same weight/viscosity at operating temp. 10w-30 is a little thicker when cold.
Long story short....close your eyes and grab one. It dont matter unless you live in antarctica.
Long story short....close your eyes and grab one. It dont matter unless you live in antarctica.
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I would just stick with the 5W30 - your car will be fine.
Le Mans Master
Joined: Sep 2013
Posts: 8,900
Likes: 1,074
From: Wisconsin
5W30 is recommended because it covers starting the car in all climate situations. W means winter. Look in your owners manual.
I would not use 5w20 0r 10w40.
Last edited by JR-01; May 7, 2017 at 09:24 AM.
Le Mans Master
Joined: Sep 2013
Posts: 8,900
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From: Wisconsin
Team Owner
Joined: Dec 1999
Posts: 34,873
Likes: 487
From: Lacey WA RVN 68-69
NCM Sinkhole Donor
IMHO, 85K is not really "high mileage". The regular Mobil-1 with the Dexos1 label will work just fine. I just bought two 5 quart jugs of the regular 5W-30 from Amazon; $22.95 per jug and free shipping with Prime. When Costco has a sale of the 1 quart bottles in a 6-pack I'll get one of those too. The quart bottle with the 5 quart jug is enough for an LSx engine.
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Le Mans Master
Joined: Sep 2013
Posts: 8,900
Likes: 1,074
From: Wisconsin
IMHO, 85K is not really "high mileage". The regular Mobil-1 with the Dexos1 label will work just fine. I just bought two 5 quart jugs of the regular 5W-30 from Amazon; $22.95 per jug and free shipping with Prime. When Costco has a sale of the 1 quart bottles in a 6-pack I'll get one of those too. The quart bottle with the 5 quart jug is enough for an LSx engine.
It's not only the miles, it's age. Some of these cars are 20 years old and additives that condition the seals are a good thing.
Last edited by JR-01; May 7, 2017 at 02:22 PM.
Melting Slicks
Joined: Jun 2013
Posts: 3,473
Likes: 691
From: West Virginia
I'm using Mobil 1 5-30 high mileage because I read that the additive package is almost the same as "ordinary" Mobil 1 was when our cars were new. Maybe someone could confirm/deny?
My car has around 75k. Uses no oil between changes (never has), has good oil pressure and no rattles, so I guess all is OK.
My car has around 75k. Uses no oil between changes (never has), has good oil pressure and no rattles, so I guess all is OK.
Safety Car
Joined: Jan 2015
Posts: 3,830
Likes: 394
From: Rocky Mountains
I don't know if it actually makes a difference, but I'm convinced the high mileage is the better option for a typical C5. Higher zinc and phosphorous compared to regular Mobil 1. It also has more group IV PAO, which is closer to the old Mobil 1 formula in use when the C5 came out. The new Mobil 1 is mostly group III base stock.
The high mileage Mobil 1 actually doesn't meet the latest dexos standard or whatever and when I investigated I found out it's because of the higher phosphorus and zinc. The latest dexos just requires the "greener" catalytic convertor friendlier lower zinc/phosphorus oil. I'm sure you can use regular Mobil 1 with good results, but at the same price, I like the high mileage formulation. I started using it at around 60k miles.
The high mileage Mobil 1 actually doesn't meet the latest dexos standard or whatever and when I investigated I found out it's because of the higher phosphorus and zinc. The latest dexos just requires the "greener" catalytic convertor friendlier lower zinc/phosphorus oil. I'm sure you can use regular Mobil 1 with good results, but at the same price, I like the high mileage formulation. I started using it at around 60k miles.
Last edited by Corvette#2; May 7, 2017 at 06:15 PM.
Pro
Joined: Aug 2016
Posts: 667
Likes: 162
From: Jennings LA
Changed oil/filter yesterday Mobile one 10w30. Only had 3700 miles on oil change before that but it was 2 years old according to records. 03 Coupe only has 110,505 miles on it at oil change. It's all good. ;-)
Safety Car
Joined: Mar 2003
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From: Philadelphia PA
Drifting
Joined: Jan 2015
Posts: 1,256
Likes: 157
From: Pennsylvania
Think of it this way you have to pour one gallon of fluid through a screen and down a tube because there are components at the end of the tube needing lubricant. Would you rather have the 30 weight get there and lubricate like it is designed to do or would you rather have a thicker fluid take longer to get to the parts. The engine was designed for 30 weight and the tolerances are specific to that weight oil 40 will increase pressure at the sacrifice of flow.
Le Mans Master
Joined: Sep 2013
Posts: 8,900
Likes: 1,074
From: Wisconsin
Think of it this way you have to pour one gallon of fluid through a screen and down a tube because there are components at the end of the tube needing lubricant. Would you rather have the 30 weight get there and lubricate like it is designed to do or would you rather have a thicker fluid take longer to get to the parts. The engine was designed for 30 weight and the tolerances are specific to that weight oil 40 will increase pressure at the sacrifice of flow.
...and 40 wt. would lead to higher operating temps and lower HP.
Instructor
Joined: Nov 2016
Posts: 186
Likes: 15
From: Elliot Lake Ontario, Canada
I've done this homework before, for my motorcycles, don't know why I didn't remember it. Anyway, the 5 indicates the cold viscosity, the lower the number the better it will flow at cold temperatures. W just indicates winter, meaning it is formulated for year round use. The 30 indicates the oil viscosity at 100 degrees temperature. So, v8srfun is correct, with 5w40, flow will be reduced at normal operating temperature. Guess I'm doing another oil change. Dammit, I knew this.
Last edited by Bob in Elliot Lake; May 13, 2017 at 09:14 AM.