Our 94 z-28 has 142000 miles on it(we've only owned it for about 2 weeks now).was wondering what type oil would you recomend the oil cap states 5w-30w should you still use such a thin oil on a high milage engine?I know on our Silverado and Avalanche I use mobil 1 5w-30w but there still under warrantee Also what about a oil additive yea or nea? Thanks Danny

 

This will probably get a fight started, but the people who actually have an oil analysis performed, and have the data to back it up, say the best oil for the LT1 is the German made synthetic Castrol 0W30. It tests to being almost a 40 wt. A lot of people will say this or that oil works for my car, but they don't have any data to compare to the people who have the data.

 

From what I've been told by a friend who circle track races, a lower weight oil is better for a car with tighter bearing clearances. When he put a higher weight oil in with his tight clearances the pressure was high. With large clearances and a low weight the pressure will be lower. With your car being a higher mile car I'd imagine the bearing are somewhat worn. Something thin like 0W30 is what my friend uses for his tight tolerances and he gets good pressure with that. Seeing ours aren't as tight, IMO you should go higher than that. I use 10W30 without any problem myself, but there are alot more options than that.

 

Wouldn't 10w30 be better than 0w30 in winter?

 

that german castrol stuff!!!! is gooooooooood!!!

 

You did a FANTASTIC job of exibiting how LITTLE you know about oil .

The 0w-30 German made Castol Syntec is a lot thicker at operating temps than M1 5w-30 or 10w-30.
The 0w-30 GC is the current oil showing the best MEASURED results, if you want to use M1 then just go with 0w-40 or 5w-40 as the M1 5w-30 and M1 10w-30 are too thin for this engine and it shows in MEASURable data from used oil analysis.
From here I I strongly encourage you to go here http://theoildrop.server101.com/cgi/ultimatebb.cgi for oil information as on this forum you will just get more BAD info like half of what you already got here.

 

I can understand your logic, but the info and reference 96caprice mentioned (minus the smart *** comment) is worth your looking into. The German Castrol 0w-30 is good poop.

 

There are two different questions floating around here. One is about weight and the other is about quality.

I'm not going to touch the quality issue, because it's like a religion, and the people who do testing are often the worst because they have all this data that they don't understand the implication of.

In terms of quality, the only thing I'm going to say is that as long as you are using one of the well known brand names and are doing oil & filter changes when you are supposed to, you'll be fine.

Hell, Quaker State Dino and 3000 mile oil changes will get you a very long service life, just for instance.


In terms of the OTHER question, the issue of weight; just use the lightest weight that insures that you have at least 10 psi of pressure at idle and another 10 psi per thousand rpm, at ANY temperature.

 

Little bit of a blanket statement there. Some like to look into the data and make their decision based on their findings, some don't.

 

I would agree that any name brand oil IN THE APPROPRIATE WEIGHT will deliver a long life, oils and engines have come a long ways and even $1 a quarts walmart brand oil is good compared to the stuff in use when 3K mile changes were recommended. The fuel injection is much more precise which makes life easier on the oil through less fuel contamination.
The factory recommendations are NOT based on what is best for engine life but rather a compromise of life and CAFE appeasment and again weights are RANGES not specific measurements so until you do some research you don't really know what is thicker and thinner or which end of the scale your engine prefers. There is also a lot more to oil than just oil there are a lot of additives with a whole range of functions.

I do not run the German Castrol but my research has shown it to currently be the oil with the best measurable results in this engine, I understand that while it may be the best that does not mean others are bad. Half an hour ago I changed the oil on the 190K LT1 in my wagon there was 5w-40 Rotella T synthetic in it, I refilled with 5w-30 Maxlife because the cold weather has the cooler lines weeping and I am hoping the seal conditioners in the "high milage" oil will help keep the leak minimal, plus it is cheaper. With winter here fuel dilution will be an issue so I will not run this oil to the 5-7K I do the Rotella. Longer drain intervals is one of the biggest benifits of synthetics and if not willing to take advantage of it you should consider a dino. Synthetic can handle heat much better as well BUT few of us will run our oil hot enough for that to matter.

If you guys read the owners manual I bet you will be shocked at what you find for oil change interval recommendations, the 3K everyone want to believe is really just a severe service recommendation these days with the b-body manuals calling for as high as 7500 on regular dino oil and we have the same exact bottomend. Now is that going to be the perfect interval and quality oil for all of us no but should help put things in perspective even if running a quality oil hard 3K is sooner than necessary and these recommendations were with the oil available in the early 90s not todays stuff.

 

Don't forget the other link in the chain.........the filter needs to be a quality one also or the dirt will just keep floating around in the oil.

 

Dotn know how good the **** is but I use Kendall 10W30 in my 96 and castroll 5W30 in my 02

 

3 in 1 oil in the tin can with Mystery Oil additive will give you about 14 more hp and in my opinion can be ran for at least 15,000 miles b/w changes

 

No need for the personal insults. I'm assuming we are mature adults. But anyways, I am quoting a friend of mine who has used these oils in his race car with the results that he saw, end of story.