Low oil pressure/ Rotella 15w40

[Tonyrodz]

One of the best passenger car/racing engines ever produced!



The aluminum truck LS engines flow 1/3 more oil per revolution and their relief spring is 33 pounds.

Aluminum block LS out of an Envoy XL.

 

[swathdiver]

Aluminum block LS out of an Envoy XL.

Gen III LM4. Each year is different so when ordering parts, need to know the year.

 

[Tonyrodz]

Gen III LM4. Each year is different so when ordering parts, need to know the year.

Motor was no good, so they scrapped it.

 

[CountryBoy19]

Oil pressure isn't everything. To a point, flow is better than pressure. Thicker oil just makes the pump and filter go into bypass sooner, giving you more unfiltered oil(oil filter bypass) and less flow at higher RPMs(oil pump bypass)

While what you're saying is true, there are a lot of other factors as well. First off, you may know this but others may not, oil pressure alone isn't what causes the filter to bypass, it's the pressure difference across the filter. And while a thicker oil will have a little higher pressure difference across the filter, I don't think it will be enough to truly effect much difference. I think the bigger thing at play is that the filter media will clog up sooner because the detergents in diesel oil will clean the engine and deposit more gunk in the filter. It's a valid concern, but often times it's a balancing act between various characteristics and traits of the various oils.

As far as the real thing going on: the fluid film in the bearing. The heavier oils will resist high loads and maintain a thicker lubricating film better. This means oil contaminants, lower flow, etc aren't necessarily as important. Note: I'm not saying they aren't important, I'm saying their importance is diminished. If we really wanted to know for sure I could get out the college textbooks on bearing design and give actual numbers for expected life with various oils. Although that would require me to remember where those books are and which book that's in... haha...

One of the best passenger car/racing engines ever produced!

I know... it's a tank! I didn't do any research before buying it, as a matter of fact, my dad used a connection he had to get it at the wholesale auction and I didn't get a choice. I gave dad a budget of how much I could spend and he brought it home. I knew nothing about it, my friends made fun of me (I was still in HS when I bought it and it's a "granny car"), but it's turned out to be the best purchase I ever made. It's a 2000, I bought it in 2004...

 

[OneofFew]

I'd like to add that diesels have cats

"
Difference between diesel oil and regular oil
Therein lies the first major difference between the oils. Diesel engine oils have a higher anti-wear (AW) load in the form of zinc dialkyldithiophosphate (ZDDP). The catalytic converters in diesel systems are designed to be able to deal with this problem, while the gasoline systems are not."

 

[SnowDrifter]

And as a point of note to that: It's generally not a problem unless you're burning a lot of oil.

Wonder if the diesel cats have a different composition than their gasoline brothers

 

[HurricaneSSeason]

"
Difference between diesel oil and regular oil
Therein lies the first major difference between the oils. Diesel engine oils have a higher anti-wear (AW) load in the form of zinc dialkyldithiophosphate (ZDDP). The catalytic converters in diesel systems are designed to be able to deal with this problem, while the gasoline systems are not."

So if you're cat delete is it a better option?

 

[OneofFew]

So if you're cat delete is it a better option?

I run it in all my catless gas vehicles and I know I'm not the only one. HD synthetic would be a good option if you are performance and economy minded.

 

[iamdub]

So if you're cat delete is it a better option?

Yes.

 

[SnowDrifter]

Tossing it out there: If you want the zinc with a little more flexibility in what oils are available, look up something called ZDDPlus. It has something like 50k ppm ZDDP if I recall. You can dose it in to your oil to a target of 1500ppm phosphorous. Yes phosphorous, not zinc. There are some other additives in the oil that have zinc in it - phosphorous is a more accurate measure. Higher than that and you can start introducing extra wear instead of protection. Do some math combined with either your own or published oil analysis of the oil you wish to use.

I think it's also worth mentioning that this is a high pressure additive. It only functions when there's a significant amount of pressure and shear on a part, in which case it forms a glass like layer. You don't see much of it in todays oils because.. Well... It's not needed. The days of flat tappet cams are behind us and these engines are pretty easy on oil. IMO if you want anti wear in a manner more applicable to our vehicles, look into ways to raise the molybdenum or boron levels of the oil