Originally Posted by Dylan1303
A word to those running Rotella T6 and other HDEOs in gasoline engines because some loudmouth on BITOG or some forum told you to. Don't. I used to tell this to people all the time; that HDEOs don't belong in gasoline engines, but I've learned a lot more lately as to specifically why that is the case.
Reason 1: Primary ZDDP. What most people just call Zinc, ZDDP is an additive package in oil that is known for anti-wear properties. I'll spare you the science behind ZDDP decomposition tiers and the nature of boundary lubrication, but what you have to realize is that there are 200+ formulations of ZDDP and they are not all equal. They come in two main categories: primary and secondary. Primary ZDDP is used mostly as an antioxidant to fight oxidative thickening in engine oils in high-heat applications, of which there are plenty in diesel engines, and is also geared more for lower friction coefficient. By contrast, gasoline engines either use mostly secondary ZDDP with some primary, or exclusively secondary (which is the case of higher quality oils), and is geared more for tribofilm formulation. Basically, your 1200ppm of Zinc in Rotella T6 is not actually protecting better than 800ppm of Zinc API SN spec synthetic oil and certainly not better than a high secondary ZDDP formulated gasoline engine oil.
Reason 2: Anti-foaming. Also referred to as air release, the oil has to release air pockets generated during friction and movement. Rotella is not very good at this, and that's OK when you are running a Detroit Diesel with a 2100RPM redline or even a 6.7 Powestroke with a 3400RPM redline (where the anti-foaming starts to become a bigger issue), not so much when you're running a Subaru FA20 with a 7400RPM redline. Under extended use, this can eventually aerate the fluid enough to cause catastrophic failure, or at minimum power loss.
Reason 3: Detergents/Dispersants. Diesel engines typically deal more with soot handling and dispersion, so the additive package is designed accordingly. On the other hand, gasoline engine detergent packs are designed more to handle acidity. This discrepancy can also result in reduced performance in gasoline engines as the detergent tries to clean the cylinder walls, which compromises the seal between rings and cylinder walls and reduces compression and efficiency.
Now I'm sure I'll get the classic "I've been using this oil and nothing has blown up yet" rhetoric by people who are too cheap to consider better options like AMSOIL, Driven Racing, Motul, and Schaeffer, but that doesn't mean that the product doesn't have its deficiencies simply because you want it to work. I realize people have a higher tendency to believe information that they agree with regarding a cheaper product than a more expensive one, but unless you already knew everything I presented in this post, you ought to reconsider your lubricant choice in gasoline engines (especially high-revving and turbo gasoline engines). There are far better options on the market.
Are you this guy, or are you just copying his post?
https://www.bobistheoilguy.com/forums/ubbthreads.php/topics/5246334/1