To Last Indian's point, the late John Sawruk, Pontiac Historian and professional engineer, would tell us that stock or near stock Pontiac engines worked best with 10W30 or 10W40 motor oil. The clearances on these motors were not as tight as those of the modern LS engines and could not take advantage of the lower viscosities of 5W30.  He recommended we not to use it unless the engine had been rebuilt with tighter tolerances by a professional engine builder.

Ok, so how does a straight 30w come into play? Behaves as 30 weight at all temps? Once you figure out the HP, max RPM and what your needs/demands are going to be how do you then decide what oil is best for you? For example, Im running straight 30 weight rotella. I was told by the counter guy at the local parts store to run straight 30 weight because my engine isn't broken in yet. Im running Rotella because it has zink and Comp Cams says to use zink additive or oil with zink in it. But after break in and oil change how do you figure out what oil to run? 

Sounds like you are running the Rotella for a combination of (A) the 30 weight and for (B) the level of ZDDP (short for Zinc dialkyldithiophosphate) for a proper break in. ZDDP is the main anti-wear component in motor oil that helps to prevent metal-to-metal contact.

As emissions rules have gotten tighter, auto manufacturers have come up with motor oil requirements eliminating phosphates to prevent catalytic converter contamination. So a lot of today's modern oils don't have the same level of ZDDP that they use to when our Pontiac engines were first produced. This is especially a problem with flat tappet solid lifter valvetrains. That is why ZDDP is such a hot topic any more.

I will leave the science of what motor oil to Last Indian. He is clearly our resident chemist and oil expert.

16 hours ago, Wrongway said:

Ok, so how does a straight 30w come into play? Behaves as 30 weight at all temps? Once you figure out the HP, max RPM and what your needs/demands are going to be how do you then decide what oil is best for you? For example, Im running straight 30 weight rotella. I was told by the counter guy at the local parts store to run straight 30 weight because my engine isn't broken in yet. Im running Rotella because it has zink and Comp Cams says to use zink additive or oil with zink in it. But after break in and oil change how do you figure out what oil to run? 

Wrongway, this particular parts guy really doesn’t know what he’s speaking of, sorry! Straight weight oil make no sense today in 99.99% of car engines! The problem with straight weight oil is cold start! First of all depending on ambiance temperature, shear stress, and or particulate, it could actually be thicker on startup! Which means the bearings could be at risk for damage because the oil pump and flow rate of the oils thickness starve the bearing for the proper film thickness! 
I would always run a multi grade oil! The Rotella is a good oil, just run a multi grade in it. If you like a 30 weight then run a 10w30 in the Rotella!

It’s not your fault! Honestly it might seem like oil should be easy, but I assure you it’s not! It’s complicated! If I asked most folk if they knew what the difference was between Newtonian fluid and non-Newtonian fluid was they would stare at me like I was from outer space! Yet in many way that is exactly the comparative difference between a single grade and a multi-grade oil!

Edited January 25, 20215 yr by Last Indian

Yeah, I back read this whole post and 1st off, wow you know your s%&t sir and 2nd, you made my head hurt and I know absolutly nothing about engine oil. I started running Rotella in my big trucks. Once I came off the road I stuck with them figuring that if they could protect those big deisel engines then they should be good enough for my little F150. So per your advice I will dump the straight 30w. But in Kentucky climite would I be better off with a 5w30 or a 10w40? Its gonna be a daily but honestly I dont get out much so she may only run 10- 20mi a week on an average week. Maybe a bit more in the summer but wont be much and hoping to drive her back up there at least once. 

On 1/25/2021 at 9:12 PM, Wrongway said:

Yeah, I back read this whole post and 1st off, wow you know your s%&t sir and 2nd, you made my head hurt and I know absolutly nothing about engine oil. I started running Rotella in my big trucks. Once I came off the road I stuck with them figuring that if they could protect those big deisel engines then they should be good enough for my little F150. So per your advice I will dump the straight 30w. But in Kentucky climite would I be better off with a 5w30 or a 10w40? Its gonna be a daily but honestly I dont get out much so she may only run 10- 20mi a week on an average week. Maybe a bit more in the summer but wont be much and hoping to drive her back up there at least once. 

With respect to your “63”, I personally would use the 10w40! Unless you’ve done something special with the bearing tolerances in some manner, of which there are several, but I presume you didn’t do any of them, so that would be my choice! 
I live in northeast Ohio! For many years I drove my Z year around! I ran 20w50 racing oil! The car sat outside! Between 1977 and the mid “80”s we had some of the coldest winters on record! Sometimes -20 without wind chill! Never missed a beat! 
One very good way to tell just how good your oil is with regard to viscosity is to run a mechanical oil gage! A good oil pressure for cold start, say ambient temp is 30 will be about 65 to 70, if you have a good high volume pump! Once warmed up in cold weather it will run around 40 in an idle. Warm weather the cold startup won’t be as high! If you get used to a mechanical oil pressure gage you can actually tell a lot about what’s going on with an engine, including when the oil has been sheared or contaminated enough to start to increase in viscosity!

Very good point about running the oil Gauge Last Indian!! i have one on my camaro👍

Ok thank you. I will switch to the 10w40. I am running a mechanical oil, volt and coolant temp gauge set from autometer. I've always like the mechanical, looks and function. Is Rotella 10w40 ok for the break in also?

10 hours ago, Wrongway said:

Ok thank you. I will switch to the 10w40. I am running a mechanical oil, volt and coolant temp gauge set from autometer. I've always like the mechanical, looks and function. Is Rotella 10w40 ok for the break in also?

Which Rotella, as there are several different series of which all have different additive packages! 
In general Rotella is a good oil to run in your car though! Most all of the T series use ZDDP, with the exception of T6, and since your “63” doesn’t use a cat they are all excellent oils! Then the only difference is conventional, synthetic or synthetic blend! I run Rotella T4 10w30 in the Indian even though I run a cat! I run the 10w30 because the 3800 is still for the most part an old skool motor!

Last indian, what are your thoughts on this Valvoline 10-30 ?

oh sorry, it down loaded the whole pdf! 

the 10w 30 on page 19

vavloline.pdf

Edited January 28, 20215 yr by 64 kiwi boni

If I remember correctly it was T1. But I'm not 100% positive. I do know it was conventional and not synthetic. I was always told not to run a synthetic in a new motor because it was to "slick" and would not let the piston rings "seal up" properly. Not sure if that's true or not so I always ran conventional unless the engines had some miles on them? So I will switch to a T4 10w40 then. Thank you for the help. Who knew oil was this complicated!

Edited January 28, 20215 yr by Wrongway

So I called the local parts house to see if they had the Rotella T4 10w40. They did not. I did a quick google search to see where I could get it around me. I couldn't find where Rotella made 10w40 in a T4. I did find T4 10w30 and T4 15w40. Is there a reason to pick 1 over the other? Our favorite counter guy also recommend car quest brand oil, saying it was just as good. Any truth to that? Also, growing up I always used Fram oil filters and never had a problem. Nowadays I keep hearing that Fram is junk.  Any idea why? Did something change or is it just not the "in thing"? 

I know this isn’t Ponti-yak but 

with my hellcat I have found a dodge dealer here in Nz that can supply me the correct oil and filter for my mopar (hellcat)

 which makes me very happy as i dont need a supercharged hemi getting anything less than what it needs !!

 

Edited February 24, 20215 yr by 64 kiwi boni