How much ZDDP in these oil ? mobil 1 and rotella

[dailydriver]

Originally Posted By: A_Harman
Originally Posted By: dailydriver
Originally Posted By: A_Harman
Many people on the GM websites advocate German Castrol, which is where the 12cSt number comes in. Some say the thicker oil helps with piston slap, others don't. One of the oil mixes that is on my list to try is M1 0w40/0w30. These two can be blended to get the target 12cSt KV100, but will have a higher VI than the vaunted GC.


We (LSx owners) all know the much vaunted 12 cSt number (WHY I mix the two Red Line grades), BUT, has anyone ever come up with a matching 'magic' HTHS value for our engine group (stock internals, of course)??!!

I tend to think that since GM specs 5w30 for the LSx engines, they're OK with the API min HTHS of 2.9cP. But since I like to have some margin, I would add 10% to that to allow for shear as an oil ages, and end up with 3.2 for a new oil. Regular M1 5w30 I think is 3.1, so maybe it's close enough. But M1 HM 5w30 is 3.3, so would be good to go. And then there is Redline 5w30 at 3.8, probably way more film thickness than the engine needs.


So you think that we are practicing excessive overkill by mixing the RL 5w-30 & 10W-40 50/50 (as far as HTHS goes), even for very hard driven, open tracked/multiple HPDE session, LS1s (given the total non-shearing of these two oils)??

Given Caterham's prompting, I am going to try the RL 0W-30, or a mix of their 0W-20 & 0W-40 (60/40, or even 70/30) over this coming winter.

 

[Torrid]

I really want to try the Redline 0w30 in mine, but considering I don't track my LS1 M1 5w30 with maybe a small amount of ZDDP additive should be more than sufficient, not to mention more cost effective.

 

[A_Harman]

The thing about Redline oils that really intrigues me is the high HTHS / low KV relationship. I like the idea of high film thickness while under shear, but relatively better heat transfer and gravity drain ability due to low kinematic viscosity. When I put Redline in my car last april, I put in 2.0qts of 5w20, and 3.5qts of 5w30. I wanted to mix the KV of the 5w30 down to ~10.0 and achieve a final HTHS of ~3.6. When I ran the car, the oil pressure was fine, but I noticed more piston slap after the engine was warmed up. This seemed different than the 9 years experience that I had with M1 in the car.

At this point, the engineer in me took over and said "aha, the louder piston noise must be due to the lower KV of the oil." So back to Lane Automotive, and buy more RL 5w30 and 10w40. I drained the 5w20/5w30 mix after only 120 miles, and refilled it with 2qts 10w40, 2.5qts 5w30, and 1.0qt of the the 5w20/5w30 mix. (I kept the rest of the 5w20/5w30 mix and will run it as a winter oil.) I went heavier on the refill because I wanted to make a large step up in viscosity to see if the piston slap would go away. It did quiet down, but I can still hear it a little. I figure that the mix has a KV100 of 11.7 and HTHS of 4.1. This is the heaviest oil I have ever run in the car, but I have not noticed a step change in fuel economy. I have noticed that oil pressure is higher when I come off the track after a lapping session and let the engine idle.

I don't think we are doing anything wrong by running the 10w40/5w30 Redline blend, because the resulting oil is still a 30-weight (according to the KV number), but it will give 40-weight film thickness (+) and 40-weight viscous drag in the bearings (-). It's a matter of the tradeoff that you're willing to make: better insurance against starving bearings for oil in a turn versus very slightly less horsepower due to higher friction.

My original plan was to run on the 5w20/5w30 mix through the summer, then change to straight 5w20 or 0w30 in the winter. But the piston slap issue (real or imagined) derailed that plan. On the next change, I'm going to put in the sligtly used 5w20/5w30 and then use 5w30 after that.

 

[dailydriver]

That's the funny thing about their 0W-30, it has a higher KV# (10.9) than the 5W-30 (10.6), but a lower HTHS# (3.2 vs. 3.8).

The wonders of VI improvers??!

Anyway, I wanted to try it for the winter due to the (MUCH vaunted by CATERHAM) higher viscosity index supposedly helping frigid 'cold' starts/wear.