Just got a 2008 CX-9 AWD. I know the fluids need to be 80-90 and 75-140. But I'm having trouble finding them without limited slip additive. I looked at the ford motorcraft ones but I'm not seeing the API gl-5 on those. Anyone know if it's ok to run these fluids with that limited slip addative in there? Or if I can use 75-90 instead of 80-90. The 75 just seems to be a lot more common.
Need help choosing PTU and Rear diff fluid for 2008 CX-9
- Thread starter Jon0m0berry
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GL-5 does not relate to limited slip additives. LSD additives do not relate to gear box operation, only to the clutches in a limited slip differential.
I found this clear description from an oil maker: "The main difference between GL-4 and GL-5 gear oils is the amount of EP additives. Sulphur/Phosphorus containing products are used as EP-additive. This additive has the purpose to prevent the occurrence of micro-welds on the gear flanks at the local high temperatures which prevail in EP (extreme pressure) circumstances (temperatures well in excess of 800℃ at the points of contact!) GL-5 has roughly twice the amount of EP additives compared to GL-4, which is why it is often used in high-pressure circumstances such as in a front axle and rear axle differential.
"Sulphur/Phosphorus additives however have an unfavourable property: they can react aggressively towards bronze and copper. This can be disastrous for the synchromesh rings of a gearbox. Therefore it is not recommended to use GL-5 in a gearbox unless the manufacturer allows this."
First, what does your owner's manual specify in addition to the viscosities...80W-90 and 75W-140? GL-5 is the more robust gear oil spec, and some state on the label that they may be used where GL-4 is spec'ed. (Did Ford supply the PTU and rear diff, or were those supplied by Mazda?) GL-5 is generally required for differentials due to it's hypoid gear capability. GL-4 is generally obsolete.
Motorcraft 80W-90 does meet GL-5 spec (MT-1 is for heavy duty non-syncro manual transmisisons):
As does Motorcraft 75W-150:
I really like Red Line gear oils, especially for difficult situations. They recommend their 75W-140 for the transfer case and their 75W-90 for the rear differential. I have found their advice to be very reliable. Their telephone number is (800) 624-7958. While Red Line products are expensive, so little is needed that the extra cost isn't much.
I found this clear description from an oil maker: "The main difference between GL-4 and GL-5 gear oils is the amount of EP additives. Sulphur/Phosphorus containing products are used as EP-additive. This additive has the purpose to prevent the occurrence of micro-welds on the gear flanks at the local high temperatures which prevail in EP (extreme pressure) circumstances (temperatures well in excess of 800℃ at the points of contact!) GL-5 has roughly twice the amount of EP additives compared to GL-4, which is why it is often used in high-pressure circumstances such as in a front axle and rear axle differential.
"Sulphur/Phosphorus additives however have an unfavourable property: they can react aggressively towards bronze and copper. This can be disastrous for the synchromesh rings of a gearbox. Therefore it is not recommended to use GL-5 in a gearbox unless the manufacturer allows this."
First, what does your owner's manual specify in addition to the viscosities...80W-90 and 75W-140? GL-5 is the more robust gear oil spec, and some state on the label that they may be used where GL-4 is spec'ed. (Did Ford supply the PTU and rear diff, or were those supplied by Mazda?) GL-5 is generally required for differentials due to it's hypoid gear capability. GL-4 is generally obsolete.
Motorcraft 80W-90 does meet GL-5 spec (MT-1 is for heavy duty non-syncro manual transmisisons):
As does Motorcraft 75W-150:
I really like Red Line gear oils, especially for difficult situations. They recommend their 75W-140 for the transfer case and their 75W-90 for the rear differential. I have found their advice to be very reliable. Their telephone number is (800) 624-7958. While Red Line products are expensive, so little is needed that the extra cost isn't much.
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