I was told by a fellow WS6 owner who works at Valvoline to not use 0W30 in the LS1. He recommended a 5W30 oil.

 

Yeah, MPGs are important to everyone. The problem I have with the manufacurers is that they recommend lighter oils for better MPG, but do not own the cars. The oil needs to take them to 100,000 miles, which is the end of emission warranty or ten years. You own the car years later and they do not care if it lasts longer.

I thought Holden was being honest with its customers and not trying to meet MPG goals alone. It recommended the oil it felt was truly best for the motor and not a government reg. Its hot in the south and the southwest and yet the manufactures recommend light oils. In Ford's case, 5-20s. Surely, its not for the good of the motor. Its good to meet regs and works well enough to take the car beyond warranty.

I submit this as an opinion, and we all know about opinions. But, the fact remains that at least in my motor there is little difference in idle pressure between the oils. So for peace of mind I use diesel, and if I opted for Pennzoil for instance, it would be 10-40.

 

The thing is, there are thousands of LS engines using factory recommended oils going 300k miles all the time, It must work...

 

Yes, but you do not know what the owners actually used. You do not know what the results would be if the same type of oil, as in SN, were used but in 10-40 weight. The 40s flow. They act like heavier oils when hot and do not thicken which is a common misbelief. Also, the engines you are talking about are OE motors in trucks and soforth. Vehicles on this forum are heavily modded which adds additional stress to engine components.

 

Castrol syntec titanium or whatever they call their full synthetic. 5w30

 

I'm talking about all the people who go to the dealer to get all their servicing done, and MANY of them do reach the mileages I mention above. The dealers would use the factory recommended oils in most cases unless the owner says different, but most wouldn't know to do that.

 

 

I think best oil choice really depends on application, how the engine is being used and what the engine builder set the motor up to use. GM even mentions using heavier oil for track day events for the 6th Gen 1LE SS and similar new cars. That can mean some extra oil changes but that's really not a big deal.
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My 99 TA had a heads and XER cam package installed at 32,000 miles. Stock bottom end & daily driver type use mostly so I used 5w-30 Mobile 1 synthetic from new to 165,000 miles. No oil related issues. Oil pressure was a solid 40 when hot at idle. My set up only made 418 whp but definitely more than stock. The 5w-30 will kept XER cam lobes & the stock LS1 lifters alive for at 132,000+ miles. However, if going road racing definitely Castrol Syntec Edge10w-40 time. Motor was replaced in quest for more hp but ran fine the day it was pulled.

389,500 miles 91 RS mostly 5w-30 Mobile 1 synthetic. The original engine ran perfect the day it was pulled for the LS swap. No oil related issues.

My 72 vette's Dart 400 was set up for 10w-40 per the engine builder. The car sits a lot is more of a nice weekends only car. The 10w-40 oil film tends to stay a little better on valve train parts than the thinner stuff. The vette also tends to see harder driving than the other cars.

In daily driver type cars, like my 99 TA most of the wear & teR happens on start up or cold start. Thinner 5w-30 or 10w30 oil that flow fast is better than thicker. Track day stuff, road racing etc definitely time to step up to heavier oil


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Not a bad analysis. The oil weight depends on the build and use. I understand that super high zinc and phosphorus levels are not necessary on roller lifter motors. But, I believe that a motor designed for say 350 HP, like my 04 GTO, when modded to make about 500 can benefit from heavier oil due to the increased pressure. For instance, most motor oil operates at about 30* above the water temperature. So, if the water temp is 210 then the oil is 240.

Oil viscosity is measured at 212. You want an oil that holds 10 or higher on the viscosity index at that temp. Most OE 10-30 oils fall into the 9-10 range at that temp. All multi forties are higher than 10. The oil I use Delo 15-40 is closer to 15. And it gets worse as temps increase. For instance, when I do 20 minute heats oil temps rise to 260-270 on my motor. I do not know the shear strength of OE oils at those temps, but I think they fall to 7-8 range or less. I know that diesel oil will still provide shear strength of 10 or higher. The same as say 10-40 Pennzoil for instance.

I am not saying that you must use an older SL oil, or advocating any other type. I am saying that the extra viscosity provides peace of mind. I hope this helps the OP here. I take no set position. I am providing my personal experiences.

 

I'm starting to think the newer, thinner oils are one reason LS's and other new engines last like they do. On startup, oil gets EVERYWHERE RIGHT NOW. Minimal scuffing due to lack of oil on startup. The oil's ability to flow very quickly to all parts of the engine goes a long way toward warmup wear. Thinner oil "slings" in a finer spray, too, helping to get everywhere SOON.

 

Yeah, that's the common belief. But, all 10-30 and 10-40 oils start with a 10 weight base. Polymers are added to give the oil greater shear strength as temperatures increase. Its all the same base stock and weight. When you use a 30W, it is actually 30 weight oil and does thin out of grade.

Also, I do not know what your experiences maybe with diesel oil, but it clings and clings. You cannot wipe it off your hands. So, I believe it provides adequate start up protection. And now I am done. I pointed out my thinking on the issue and you decide for yourself.

 

Just to give you an idea of what I've personally experienced.. I bought my 2000 SS with 137k on it, I immediately went to work on it and had it tuned, did intake and headers and LS6 valve springs and turned the rev limiter to 6900. I BEAT and I mean reallllly BEAT the dog **** out of that motor every single day. No exaggeration, until I sold the car with 191k on it. The next owner raced it a lot and the guy after him. Car was totaled at 220k and consistently pulled on cammed cars. No engine issues. My 2004 Sierra.. I got it with 80k, same thing went and had it tuned immediately, rev limiter 6500 and drove it very hard daily. I like to have fun on my commute. Sold it at 190k, not a single issue with the motor and held 45-50 ish psi at idle and around 80 psi while revving.

The camaro I usually ran conventional and changed the oil at 2500-3000 miles, the truck I ran synthetic and ran about 8000 miles per oil change. Ran recommended oil weight in both.

On my 95 GSR, I had a LS bottom end that was factory rated at 6800 rpm rev limit, I took it to 8100 daily for 2 years with a turbo at 7 psi, ran recommended oil and it finally died when I accidentally let it get low on oil and did a 8k rpm 5th gear pull against a gsxr on the highway.

So me personally, I've had excellent luck with "thin" oil mixed with lots of abuse.

However, I wasn't stupid with things either, I always made sure everything was up to operating temp before hammering on it and in general was smart about the hammering.

I know this doesn't prove anything for all cars or situations, just figured I'd give you some info to add to your mental data base.

Thanks for sharing the in depth stuff, I'll go through and read thoroughly soon.

 

Great Blog!

FWIW:
For literally decades I have been using Mobil1 5W-30 or 10W-30 with ~10k change intervals and ALL the engines look like "honey" inside even at 200k miles on them. Also the recommended factory fill for GM perf cars (and others). Plus look at the price point! M1 for ~$25 5 qts jug at Wally World, look no further!

IMO stick with what works IDK why people overthink this. (money no object I would go Amsoil, but for double the price the reward isn't there)

 

I run full synthetic throughout the entire engine's life, even when new. Synthetic is proven, and far superior to conventional oils in every way possible. I would not be interested in purchasing an engine nowadays if I had knowledge of a previous owner running conventional oil or "diesel" oil in place of the correct oils. I personally prefer Mobil 1 or Valvoline.

 

My 2500hd is at 300k and still runs like new and when I did the pan gasket it looked perfect inside zero sludge just a nice caramel coloring. I run Rotella 15-40 and it has treated me well. For what it's worth I live in Texas and it's hot lol

 

A little something about synthetic oil. The difference between it and conventional is that the molecules are broken down and reassembled. All oil has different sized molecules. So, the lubricated parts tend to ride on the larger molecules. When the oil is synthesized, it is broken down and the molecules made smaller and uniform in size. This makes it flow better. That's why it was developed for jet engines which must operate almost constantly at 35 below.

The makers are supposed to use base stock 4 oils. But, in recent years they have been allowed to use Base 2 and 3 stocks, the same as conventional oil. They are allowed to call it "synthetic" because it is processed differently than conventional oil. Very few base 4 synthetics are made because of cost. Redline and Amsoil for instance still use base 4 stocks and you pay up for it. Mobile 1, Pennzoil, etc. use base 3 and 2 stocks.

Advances in cracking conventional oil have made it similar in quality to synthetics. Delo 400 is made with the "Isosyn" process and is nearly as uniform as synthetics. It uses the same base stocks 2 and 3. I not flying a jet. So, why pay up substantially for oil that is good to 35 below. This is true of most conventional oil today.

Also, because of cost people tend to do more frequent oil changes with conventional oil and drain any contaminants out. I am not saying you will not have good results with synthetics, I am saying why pay more? Finally, the reason you can buy Mobile 1 and others relatively cheaply is because those oils are not using base 4 stocks. But, to say you would not want a car that used diesel oil before is wrong. BTW, you can use diesel oil in a gasoline motor, but not motor oil in a diesel. Besides, I also use it for the Harley. I hope this sheds some light.

 

INCORRECT!

The 2 highest PSI scoring oils out of the bottle in the referenced blog, with no additional additives,
(except by the original manufacturer)
were # 2 AMSOIL Signature Series 5W-30 and
#1 AMSOIL Signature Series 0W-20.
BTW AMSOIL does not market or even refer to this specific test in any of its marketing material.
(Full Disclosure... AMSOIL User & Dealer since 1989)
Both of these oils are low ZDDP, below 1000 PPM and with regard to GL-5 additives I am quite sure you are not privy
to their formulations. They also provide very little loss of protection @ 275*
With the onset of Thermal Degradation @ 290*

 

and number 5 in the test was mobil 1 0-40 euro formula

I would gladly use the amsoil if it were 23$ in a 5 qt jug like the 0-40 is priced at wally world !! ( if you can get me that deal contact me !!! )

 

What came in 3rd and 4th?

 

He also tested at temperatures under 230°F as well as at and over that temp, he also showed the test results at 275°F. Based on that, I'll be trying the Amsoil Signature Series 5w30 synthetic and see how the oil analysis goes. That type of amsoil costs $11 ($14 CDN) per liter at my local speedshop, not too bad.