Vette(s): 1973 Coupe -- 454 / 4 speed - Black on Black, Greenwood aftermarket turbo hood, Greenwood GTO style front bumper.American Racing Vector rims.
sundevil74 said: Not sure where I read it (a few years back), but Shell's Rotella T in viscosity 15W-40 was recommended, especially for older engines. It is designed primarily for diesel engines and trucks. I've been using it ever since. If I can find the article, I'll post it.
Use it myself. Got turned onto it by my son who builds 4 cylinder turbo engines. He gave it high ratings and said the import tunners swear by it. My Big Block likes it also.
I read somewhere that 10w40 weights and higher do not have to meet the lower zinc requirements for modern emission systems.
Shell took the zinc out of their oils just like everyone else though.
F4 - Well you got me thinking about your post regarding the fact that Shell removed the Zinc from their Rotella T series of oil so I did some digging on the net.. The most current post regarding this rumor about Zinc content was posted in 2014 by a gentalmen that asked Shell technical staff about the Zinc content of Rotella T series oils. They stated that the Zinc content had been REDUCED to 1200 ppm in their oil but was still twice the amount of regular API olis. There is a lot of discussion on the net about this topic so I guess the debate continues. I did read caution should be used running higher zinc level oils in vehicles with cats due to tge fact they can be damaged from the zinc but then those emmision engines shouldn't need the added zinc anyway. Thanks for your post F4 it stired the pot regarding this subject. The debat continues.
"Only the 15W-40 and 5W-40. Those grades are NOT bound to the <800 PPM
standard to be rated as an SN. The 10W-30 is SN rated and that grade is
required to have less than 800 PPM. The detergent levels in these oils
are way higher to pass the CJ-4 qualifications. Detergents are polar
molecules as is ZDDP. They fight for the same space and reduce the
coverage of ZDDP on the extreme pressure loaded parts. This is why
diesel oils have higher levels, they have to to provide similar
Vette(s): 1982 C3 Collectors Edition 44000 miles, sat in the sun most of it's life, My wife purchased it for me for fathers day in 2007 from her girl friend that had it for 19 years. It is on the road again. I'm retired but it is now my daily driver.
This is what Pennzoil oils said in 2012.
An API SM rating will have the reduced zinc content (800-850ppm) while those such as the Pennzoil Outdoor Motorcycle Motor Oil in both SAE 10W-40 and SAE 20W-50 with the API SH will have 1100-1200ppm zinc.
Other oils containing higher zinc levels will be any oil with a diesel rating, API CI-4 or CJ-4.
The Shell Rotella SAE 15W-40 contains 1100-1200ppm zinc and Pennzoil Racing Motor Oil SAE 25W-50 has 1980ppm zinc.
I could not find any specification from Pennzoil on their products.
One Pennzoil issue that is not reported much and I bet has not gone away is it depends on location the oil is manufactured to be sold in and the time of the year. There are different additive packages for it so it is difficult to know what you are getting from Pennzoil. I saw some test results from supposedly independent labs that show anywhere from 800ppm to 1800ppm for the same supposedly oil.
Also Racing oils are designed for racing fuels not street fuels. There is lots of different opinions on the harm or benefit of using Racing oils in street machines as the frequency of changing oils in a racer is a lot more than you want to do in your street machine.
Oh by the way I have read in a couple of oil forums that most sealant material used in pre-1992 engines does not like Synthetic motor oils. Just thought I would through that into the mix. I personally do not use synthetic oil in my 82.
Vette(s): 1981 Corvette Two-Tone Claret color, 4 spd,
FYI, If you going to add a thick additive do it when changing oil and add it to say a 1/2 quart of oil or in my case a 5 qt container and shake it up to make sure it gets distributed. If it's just poured in on it's own it's gonna just cling to the side of the block and flow to the bottom of the pan.
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