Question: “Is Spectro Heavy Duty 6-Speed GL-5 transmission oil safe for yellow metals (bearings, bushings) in the transmission? Your data sheet indicates a GL-5 rating. Some discussions, including the Mobil-1 website, state that the additives in GL-5 oils are detrimental to “yellow metal” parts in the transmission. Is your GL-5 transmission oil different?”
Answer: “Spectro 6 Speed is GL5 rated but is safe to use in GL1 applications. We use a different formula (developed by Spectro) than other brands that is buffered. This formula will not attack “bright” metals such as brass, bronze and copper found in older transmissions. It’s more expensive to produce, but we feel the performance is well worth the cost. It also improves shifting in most applications, reduces noise (5th gear whine in HD 6 speeds) and is highly resistive to shear and loading. Spectro Oils Of America.
(if you questions regarding engine and transmission oils or suspension fluids you can submit them at info@spectro-oils.com. Will publish the most interesting ones)
FYI, Baker Drivetrain recommends Spectro in their trannies.
S&S too, I think.
Good question and a good answer.
When customers call to order our Dimple Magnetic Oil Plugs we ask what kind of lubricant they like and Spectro has been a frequent answer along with some others
Customers like the best oil they can get but insist on removing the hundreds of tiny metal particles, the majority of which cannot be seen by the naked eye.
I’ve been using their Heavy Duty 6-speed oil for about three years without issue. It does indeed cut down the gear whine.
Like this Q&A thing. Keep them coming.