The Ford Barn

grumppyoldman · 08-01-2019, 11:32 AM

What gear oil should be used in the rear end 0f a 55 Fairlane with an 8" 3;30 to 1/ ratio? Al

estout81 · 08-01-2019, 12:26 PM

I use 90/140 in my '48 and '51 Ford. Both have stock rearends.

Daves55Sedan · 08-01-2019, 11:50 PM

90 wt gear oil is recommended for a stock rear end. If it has been converted to posi-track, you will need to add a tube of posi-lube. Does not matter what the gear ratio is.

grumppyoldman · 08-02-2019, 12:14 PM

the climate down here is hotter than where you guys live, so I think I should use the 140 wt. thanks for the info. Al

rotorwrench · 08-02-2019, 01:39 PM

I use SAE 85W/140 for south Texas climate. Northerners can us the SAE 80W/90. It's getting harder to find the straight grades. I have to buy SWEPCO 201 SAE-90 for the Robinson helicopters due to there specification for straight grade only with a blue color so you can tell it's in there. That stuff is more expensive than the SAE 85W/140 at the local lubricant supply distributor we use.

slumlord44 · 08-04-2019, 12:07 AM

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If my memory serves me right it must be HP rated.

rotorwrench · 08-04-2019, 10:19 AM

I can't remember how good my memory is. Gear lubricants are EP rated for the content of extra pressure additives. Rear axles generally have no phosphor bronze bushings unless they are very old worm drive types so it really doesn't matter what EP rating is used. Hypoid type axles really should have EP5 if they are used a lot for hauling heavy loads such as in a large car, pickup, or a large truck otherwise an EP4 would work.

Transmissions from the early ford years have the soft yellow metals so they should use EP4 or less to prevent acidic deterioration of the soft metals.

Ole Don · 08-04-2019, 03:12 PM

Most of the diffs spoken about above have a brass piece behind each of the spider gears.

08-01-2019, 11:32 AM	#1
grumppyoldman Senior Member Join Date: Apr 2017 Location: Texas Gulf Coast Posts: 727	Rear eend gear oil What gear oil should be used in the rear end 0f a 55 Fairlane with an 8" 3;30 to 1/ ratio? Al

08-01-2019, 12:26 PM	#2
estout81 BANNED Join Date: Jun 2010 Location: Utica, Ohio Posts: 522	Re: Rear eend gear oil I use 90/140 in my '48 and '51 Ford. Both have stock rearends.

08-01-2019, 11:50 PM	#3
Daves55Sedan Senior Member Join Date: May 2010 Location: Granite City, Illinois Posts: 3,008	Re: Rear eend gear oil 90 wt gear oil is recommended for a stock rear end. If it has been converted to posi-track, you will need to add a tube of posi-lube. Does not matter what the gear ratio is.

08-02-2019, 12:14 PM	#4
grumppyoldman Senior Member Join Date: Apr 2017 Location: Texas Gulf Coast Posts: 727	Re: Rear eend gear oil the climate down here is hotter than where you guys live, so I think I should use the 140 wt. thanks for the info. Al

08-02-2019, 01:39 PM	#5
rotorwrench Senior Member Join Date: Jun 2010 Location: San Antonio, Texas Posts: 16,432	Re: Rear eend gear oil I use SAE 85W/140 for south Texas climate. Northerners can us the SAE 80W/90. It's getting harder to find the straight grades. I have to buy SWEPCO 201 SAE-90 for the Robinson helicopters due to there specification for straight grade only with a blue color so you can tell it's in there. That stuff is more expensive than the SAE 85W/140 at the local lubricant supply distributor we use.

08-04-2019, 12:07 AM	#6
slumlord44 Senior Member Join Date: Jun 2017 Posts: 104	Re: Rear eend gear oil Sponsored Links (Register now to hide all advertisements) If my memory serves me right it must be HP rated.

08-04-2019, 10:19 AM	#7
rotorwrench Senior Member Join Date: Jun 2010 Location: San Antonio, Texas Posts: 16,432	Re: Rear eend gear oil I can't remember how good my memory is. Gear lubricants are EP rated for the content of extra pressure additives. Rear axles generally have no phosphor bronze bushings unless they are very old worm drive types so it really doesn't matter what EP rating is used. Hypoid type axles really should have EP5 if they are used a lot for hauling heavy loads such as in a large car, pickup, or a large truck otherwise an EP4 would work. Transmissions from the early ford years have the soft yellow metals so they should use EP4 or less to prevent acidic deterioration of the soft metals.

08-04-2019, 03:12 PM	#8
Ole Don Senior Member Join Date: May 2010 Location: St. Michael, Minnesota Posts: 1,713	Re: Rear eend gear oil Most of the diffs spoken about above have a brass piece behind each of the spider gears.