Oil Weight - Chevrolet Forum - Chevy Enthusiasts Forums
Old  May 7th, 2009, 11:31 AM
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Oil Weight

What is the recommended oil weight I should use for my 03 Tahoe, 98,000 miles.

Old  May 7th, 2009, 11:42 AM
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Most all GM cars use 5-30, I switched to 10-30 after it hit 75,000mi , but that was just a personal preference.

Good question, Id like to hear when its time to use a heavier weight if at all from the GM Techs here.

Old  May 7th, 2009, 12:31 PM
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Dave aka:ZX1100F1 had this on the topic...

"5W30 oil is good to go for the hot temperatures of the South, GM no longer recommends 10W30 or any thicker viscosity.
If you are concerned I would recommend using synthetic oil."

Old  May 7th, 2009, 12:41 PM

Read the manual... it will tell you what to use.

my 95 and 09 tahoe both say 5w-30 so that's what they get!

the Jeep is 5w30 too I think... but I only change the oil once a year with it... it only went 1800 miles last year... full synthetic...

the Ford (mazda) in the family uses the 5w-20 stuff, as do a lot of new engines

I think ford runs something off the oil pressure in its engines...

anyway, read, and stick to the manual. they didn't write it for their health...

Old  May 7th, 2009, 3:20 PM
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I understand the manual recommendations, but some higher mileage engines need more oil weight as they wear. If it is a fact that you can continue to keep using 5-30 in Chevys after passing 75,000-100,000 miles then I will be switching back to 5-30 next change.

I use Full Synthetic, always have , always will

Old  May 7th, 2009, 4:16 PM
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I have always use 10w30 in my Blazer and Silverado even though it says 5w30. I can't imagine it making that much of a difference. The Camaro gets a good healthy fill of 10w40

Old  May 8th, 2009, 7:53 AM

I agree with your logic, however if that was the case; I think they would put it in the manual... I have 219,500+ on my 1995 Tahoe with 5w-30 since day one, since that's what the cap says...

I could see using the 'high milage' oils in something with 'high milage'... but today's engines are really well designed / built things that have a lot of life in them... 100,000 isn't exactly high milage when I've seen Suburbans over 300,000 its 1/3 milage... lol...

I think between the 1960s and 1990s the yardstick of where an engine 'wears out' has been moved litterally miles down the road...

I better see 300,000 from my 2009 Tahoe as I saw 220 from my last one (and it still runs fine! all stock!)

As for the oil: http://www.upmpg.com/tech_articles/motoroil_viscosity/

explains that the 5w is the cold side... where the 5 means the oil is thinner than the 30, when the engine is cold.... the oil actually gets thicker as it heats up...

going from 5w-30 to 10w-30 just means you have a thicker oil when the engine is COLD.

Unless you only drive 2 miles at a time, your engine will be at 210 in no time... meaning that while running at 210... there is no difference between the two oils...

I'd stay with the 5w, since its thinner, it gets pumped around faster at startup to protect things....

unless your saying that 5w is so thin when its cold that its leaking out of your engine...

are you in a cold climate or warm or hot? My 1995 says its 'okay' to run 10w-30 if it never gets below 32 in your area, since at 32 I would think 5w and 10w are the same... but 5w stays thin below 32 for starts.... I live in PA, so it does sometimes get below 32....

the other advantage you might see from 10w-30 is that it has more 'oil'... it does this by having a lower % of chemicals that make it do the cool thin to thick thing than 5w has...

it's your engine and your choice, doesn't that make it fun?!

Old  May 8th, 2009, 9:35 AM
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Synthetic oil???

Well the manual says 5w-30, the oil cap says 5w-30, so why use systhetic oil? the cost of the oil is double.....

Old  May 8th, 2009, 9:58 AM
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Use what you will, I think we have all explained it the best we can. Using synthetic oil will add to your engines life span if my opinion, I believe these newer engines recommend at least a synthetic blend, it says that in my manual. All in all, if your not sure, go by what your manual says, you cant do any harm.

Last edited by Mike Sigmond; May 8th, 2009 at 10:08 AM. Reason: spelling
Old  May 8th, 2009, 10:08 AM

Synthetic vs dino is a whole nother topic that would need its own thread

This one is for the weights...

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