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5W-30 is what is recommended for these engines, 10W-30 maybe in the hotter parts of the world and appropriate seasons. Castrol GTX high mileage is what I have always used. I like to add Seafoam before every other oil change if I can remember, once a year is probably enough if you stick with the change intervals.

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5W-30 will bring any 3400 far beyond the mileage necessary to kill a transmission or two or three... if you really want to treat the engine to something special, run 0W-30.

 

if the engine has gotten really sloppy and otherwise has pressure issues at full temp, a 40 weight oil will usually limp it along for quite some time. 5W or better yet, 0W if necessary.

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why 5w 30? i kn new its tht wat bout older? will thicker oil cause more top end noise?

 

Because that's what GM built the engine to use. The oil weight is just a reflection of how tight or loose the oil passages are. This is why European cars run 0w20. Some Euro engines (BMW and VW come to mind) have very tight oil passages, so they can run a lighter oil. Some engines (AMC/Jeep 4.0, Buick 90 Deg. V6) are built with larger oil passages, thus the need for 10w30. The weight is usually dictated somewhere on the oil cap, a sticker in the hood, etc or the owners manual.

 

The only time you need to change oil viscosity is when your engine is in an extreme climate or if there's engine issues. For example, you can run 30 or 40 weight in the middle east due to no freezing conditions in that area, and you can run 0w30 in an Alaskan car. The first weight is the winter weight, hence 0W, 5W, 10W. The lower the number, the thinner it is, and also harder for it to freeze. 10w will be harder to use in a very cold climate than 5w or 0 w. The same is reverse. the heavier the weight, the thicker it is when the engine is in hot running condition. The numbers usually have a temperature rating. For example, the 3800 typically uses 10w30. In this application, you can't drive the car if it's past -20 unless you have an engine block warmer or something like that. It will be harder for the oil to flow in that temperature compared to 5W30. The other one is warmth weight. The higher the number, the thicker it is.

 

Now, I persoanlly run 10w40 on my 3800 Camaro. I wanted to run 50 weight but couldn't find it mixed. The reason I do this is because my oil pump is bad. The engine was actually flooded with water, so what would happen is that the oil pressure dropped as the engine ran warmer. This is also why you would run a thicker weight. If the passages or the pump are bad, you need to compensate by weight.

 

With all this said, your car should specify 5w30. Stay away from any other weight unless you're under an unusual situation.

 

Read this. It explains it better than I'll ever be able to.

 

http://www.amsoil.com/lit/g52.pdf

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0W-30 here.

 

If you read the specs, the 0W-30 is actually thicker at operating temperature than most 5W and 10W-30's. And of course, thinner in the cold. Unless the cost is a major issue, practically every W-body application can safely (and probably would benefit) from running 0W-30.

 

[video=youtube;OWiQyR7PWII]

 

Its specific to one vendor (Esso/Imperial Oil), but a good general description of what's so great about the 0W-30 weight including nice visual examples.

Edited by pitzel
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I ran 10W30 in a 3100 once. It did NOT like the 10W30. Made all kinds of odd noises. Drained that shit out immediately and went back to 5W30.

 

Stick with 5W30. Correction, stick with whatever the manufacturer recommends (it's printed on your "710" cap - LOL)

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well ok its my 2000 buick century tht i swapped a 3400 from impala its pretty much rebuilt besides lifters i kn dumb of me i should have while doing intake gaskets but im smart to do upgraded metal gaskets tho lol but anyway especially when cold start lots of lifter noise like clatter when using 10w 30 but goes away when warm but jt recently switch to 15w 40 detergent oil and reduced lifter clatter but will be switching oil again back to 10w 30 full synthetic

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............................................................................ why 10 and 15W oils? if you're going spend more money on a synthetic, why get something with horrible cold-temp characteristics?

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............................................................................ why 10 and 15W oils? if you're going spend more money on a synthetic, why get something with horrible cold-temp characteristics?

 

Truth be told, practically any motor oil sold today with the latest API spec (the so-called 'donut') is far higher in quality than what was available at the time most W-body cars were manufactured. And these engines, even the 3.4, are not particularly hard on oil. But yeah, most wear occurs during start-up, so anything that gets the oil flowing better right after startup can't be a bad thing. I've never heard of a W-body engine actually wearing out or being otherwise damaged due to the selection of oil though. Its usually coolant contamination, or simply other non-oil-related maintenance issues that lead to the demise of these engines.

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You'll burn more fuel with the 15W-40 on account of higher pumping losses. It will take longer to reach critical components in the car upon startup. And there is no evidence whatsoever that, at operating temperatures, the 30 weight is inadequate. Nor do these engines (with perhaps the exception of the turbochargers in the TGP's) actually run hot enough to warrant the higher viscosity.

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Truth be told, practically any motor oil sold today with the latest API spec (the so-called 'donut') is far higher in quality than what was available at the time most W-body cars were manufactured. And these engines, even the 3.4, are not particularly hard on oil. But yeah, most wear occurs during start-up, so anything that gets the oil flowing better right after startup can't be a bad thing. I've never heard of a W-body engine actually wearing out or being otherwise damaged due to the selection of oil though. Its usually coolant contamination, or simply other non-oil-related maintenance issues that lead to the demise of these engines.

 

even someone determined to run the most incorrect oil they can find(20W-50) will rarely kill an engine specifically because of oil choice..... unless they get ahold of and run some straight 30/40/50 or SA-spec'd dollar store oil or something crazy like that.

 

but yeah..... there is absolutely no reason to do anything of that nature. that path has no benefits, only drawbacks.

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Agreed. I'd stay clear from the thicker winter grade oils, basically anything above 10w. I ran 15w40 for a couple of cycles last summer thinking the same as far as being a detergant, but learned it was more likely a nuisance than good..especially in the cold. The additive packs in a passenger car motor oil are way different than a HD/diesel engine oil spec. Stick to whatever the factory specs are.

 

10w30 GTX High Mileage in my Regal, and whatever API approved 5w30 in the Impala.

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