So, I went out and dug in the trash out of curiosity, and found some of the Castrol HD30 qts from a previous oil change. They were API SL rating, when the phosphorus was higher. And the new 5-30 Syntec was SM low phos, and within 1,000mi of switching over from the SL to the SM, my thrust bearing crapped.[:@]

I checked it today, not totally assembled since I'm waiting on some Canton stuff, but with the crank wear from the burnt bearing, my thrust is around .035". Rather high, but with some bearing modification to increase oiling to the loaded thrust face, I should get by for a while so I can avoid changing my crank in the short term.

 

I highly doubt that the difference from that one oil change was enough to destroy your thrust bearing. I have been running low ZDDP oil for a while now and havn't seen engine failure...oh wait, thats right its being rebuilt because of ring failure. But the bearings and crank were fine...oh well, I guess we will never know how bad it could have been b/c I will be running high ZDDP oil from now on. Sorry about your crank man.

 

Thrust surface wear is mostly a function of how heavy of a clutch you're using and how much time you spend idling in gear with the clutch disengaged.

my77 - I seriously doubt that 5W20 will be much different cold than 5W30. 0Wsomething would be expected to show lower cold pressure.


Norm

 

i never understood oil having a weight rating of 0

thats like when they say its 100% humidity but its not raining. wtf?

 

Absaflogginlutely!!!!!!

 

Understand that the viscosities listed on the oil containers are relative viscosity numbers. Not absolute viscosity numbers, which look quite different and have strange-looking units. IOW, the 0 is only a number relative to 5, 10, or whatever - that you can interpret to mean "less viscous at the low temperature", or "thinner when cold than 5Wxx". It does not mean "no resistance whatsoever to flow".


Norm

 

Considering I was running the same clutch the entire time, with the same setup and proper adjustment, and don't ride my clutch(I actually try to spend as little time on it at low speed as possible), and was running the same clutch setup on the PREVIOUS engine that went over 100k without a single issue(aside from the people who build it using too light a valve spring and the #1 piston was too tight), and the ONLY thing about the entire setup that changed was the ILSAC/API specification in the oil, I think I can safely assume it's the oil. Certainly it could be something else, or perhaps just a freak failure, but the recent use of the low phosphorus oils seems to coincide with a sudden and unexplainable(other than the oil) increase in lubrication related failures where there were none previously, particularly thrust bearings(the guys who does machine work for me said he's recently started to see a lot more thrust bearing failures where the only thing different was the newer oil). We've known for a while now that the decrease of ZDDP in engine oil presents a problem for flat tappet cams, since they experience very high shear, so it stands to reason that further reductions in anti wear additives will results in more failures related to the higher shear areas in an engine. I even read several old articles(from 2004ish) in several lubrication related journals, where serious concerns were expressed over whether or not the new GF-4/SM oils would be backwards compatible with older engines(like they're supposed to be). They were worried that any engine manufactured prior to 2005 could potentially be at risk for lubrication related failures due to the GF-4/SM requirements for oil additive content.

 

Alternatively, you could just use a "High Zinc" motor oil, like MotorHead "Hi-Z" Classic (www.MotorHeadOil.com). I use their ZDDP additive (its called ZBoost). A one ounce bottle will raise the zinc (and phosphorous) level of 5 quarts of ANY API-SM rated motor oil by 700 ppm (580 ppm for a 6 quart oil change). I use it with the 5 quart jug of Pennsoil that Walmart sells, and it only costs me $9.95 with free shipping. That's a hell of a cheap price to protect a cam.

 

a 0W oil should have the same viscosity as water when cold

 

I will be putting my engine in soon. The guy working on it forme says to run regular valvoline on break in. He doesnt seem too worried about the zinc. I am thinking about switching to amsoil after about 5000 miles. Should I tell him I want to run the Valvoline racing oil right away or what? Thanks