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Old 04-18-2016, 06:49 PM   #1
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Default GL4 or GL5 gear oil read this

This explains why GL5 is not to be used where GL4 is called for, it's long and not all of it will apply to the Nissan but it has a lot of good info:


" It is extremely common, or normal, for all GL-5 oils to claim they cover the API
GL -4 requirements for gear oils. This is a true statement. Does that make them
satisfactory for synchromesh or synchronized transmissions? NO!
They meet the GEAR OIL specifications, not transmission oil specifications. The
API GL-4 and GL-5 categories do not mention or have anything to do with
transmission synchronizers."

"In normal operation, the sulfur/phosphorous additive forms a black sacrificial
coating on the gears and anything it touches with a little pressure and
temperature. As the gears turn, instead of wearing, the sacrificial coating
of additives is pealed off or worn off. This is normal and acceptable in all steel
gears. But when one or more of the surfaces is brass or another soft metal, the
sacrificial coating is stronger than the base metal, and instead of just
peeling off, it takes with it a few microns of brass that it is bound to."

"When we use a GL-5 product in a transmission that requires
GL-4, we normally find 2 to 4 times as much copper in the used
oil as we would with a GL-4 product(with used oil analysis)"

"Just remember that GL-4 and GL-5 are gear oil ratings,
not transmission oil ratings. Transmissions have gears and
synchronizers. These seemingly conflicting requirements must be met differently.
When someone tells you that their GL-5 covers GL-4, remember they are
correct as far as EP protection, but that is only half the answer. When
they say their Sulfur/Phosphorous additive will not corrode the yellow metals,
they are also correct, but if there are enough to meet GL-5 protection, they
will slowly peel away your brass synchronizers."

"Here is a simple explanation of the problem from Nissan:

If Nissan service manual asks for API GL-4 rated oil than you have to use API GL-4 oil. GL-5 is NOT made to replace GL-4.
Do not use GL-5 it will destroy your transmission. "
My name is Tony and I'm a Infamousaholic

Current truck - 2017 Nissan Frontier Desert Runner ,

(formerly owned: 1993 Nissan Hardbody king cab 2wd, 90 Nissan Sentra, 94 Nissan Pathfinder SE 4x4, 05 Nissan Titan, 87 Nissan SE-V6 4x4 king cab, 94 Infiniti Q45t & 80 Datsun 310GX )
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