When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
For oil I use Mobil 1 10-30 synthetic high mileage.......A lot will say use Amsoil...I'm not cheap, but I'm not paying 9-10 dollars a quart....
Oil related failures are insidious. Often by the time you have issues, it is waaay to late to correct a decision on something so critical as oil.
With that in mind, the Mobil 1 oil that has the ZDDP levels recommended when the LT5 was built is their Mobil 1 15W-50 (having1200 and 1300 ppm phosphorous/zinc.
Recently, according to their published spec sheet, Mobil 1 has reduced the concentrations of phosphorous/zinc in their HIGH MILEAGE formula to a fraction of the ZDDP concentrations recommended in 1990 for the FLAT TAPPET LT5.
A better compromise might be their Mobil 1 "FS X2" 5W-50 at 1000/1100 ZDDP levels.
The point is, just about any oil in the 10W-30 or so may work...for the short term; especially if the car is not raced or seldom sees RPM near the 7000+ range. Once you have a lifter "explode" (and I've seen a couple that did) - where the cam lobe burns through the thin metal top of the lifter(s) and the lifter shatters, scattering bits of metal among cams, bearings, and other lifters, you're looking at pulling the motor and cam(s) to inspect it and then reassemble...working on a DOHC motor is just a leeeetle bit more complicated than OHV SBC!
Yeah, Amsoil IS expensive. But, it is durable and for normal driving good for 7+10k miles (at least). So, changing oil every other year (5-6k miles) is no bigh deal, and the peace of mind that having the right stuff in the crank case is comforting.
2020 Corvette of the Year Finalist (performance mods)
C4 of Year Winner (performance mods) 2019
Someone on Bobistheoilguy performed a new oil analysis on Royal Purple HPS and got really good results on it for zinc and phosphorus levels, which combined with being readily available from Amazon is why I started using it.
All samples were taken from brand new, thoroughly shaken bottles of oil. And all tests were performed at ALS Tribology, formerly Staveley Labs, in Sparks, Nevada.
Royal Purple 10W30 HPS (High Performance Street)
Silicon = 7 ppm (anti-foaming agent in new oil, but in used oil, certain gasket materials and dirt can also add to this number)
Boron = <5 ppm (detergent/dispersant)
Magnesium = 46 ppm (detergent/dispersant)
Calcium = 3626 ppm (detergent/dispersant)
Barium = <1 ppm (detergent/dispersant)
Total detergent/dispersant = 3676 ppm
Zinc = 1774 ppm (anti-wear)
Phos = 1347 ppm (anti-wear)
Moly = 189 ppm (anti-wear)
Total anti-wear = 3310 ppm
Potassium = 11 ppm (anti-freeze inhibitor)
Sodium = 2 ppm (anti-freeze inhibitor)
TBN = 10.2 (Total Base Number is an acid neutralizer to prevent corrosion. Most gasoline engine motor oils start with TBN around 8 or 9. And in use, this becomes depleted over time as mileage accumulates)
Viscosity (cSt at 100*C) = 11.3 (cSt range for SAE 30 is 9.3 to 12.4) And cSt (centistokes) in general terms, represents an oil’s thickness.
Haibeck used to recommend Mobil1 High Mileage as one of the options due to it's high ZDDP (zinc & phosphorus), but since their reformulation, I'd avoid it. The LT5 really needs high level ZDDP oil, and I would definitely pay attention in what you select. Haibeck has a good article on why here.
Opinions please: '91 ZR-1 with 54,000 miles. Not driven hard (by me anyway). With Mobil 1 10W30, is a Rislone 4405 oil additive with zinc additive good, bad or indifferent? Michigan car, driven only in warm months.
Mike
04-26-2019, 11:14 AM
Fluid/lubricant
