Differential oil

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Michael Bayer
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Joined: Mon Nov 04, 2002 7:22 am

Differential oil

Post by Michael Bayer »

Ok guys, time to change the diff in #9727, where the heck do you find 250 wt? Is there a better alternative, now 35 years since the spec? Michael Bayer
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tyang
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Post by tyang »

Hi Michael,

Look at this link:
http://www.tomyang.net/cars/ferrari.html?gearoil.htm
It's in the "tips" section of my website in under "lubrication."

There are a lot of opinions on the 250 wt. oil. Most people put 80-90 without problems. Some people feel that the 250 wt. was for high speed driving, and the heavier wt would not loose it's vicosity at the higher temps, while others feel that the thick oil also helps quiet the rear end and prevent leaks.

I found the penrite oil in 250 wt. so I went ahead and put it in my car and it seems to work fine. I'll be changing it soon to wash any more water out of my differential. It's long story, if you haven't read about it!
http://www.tomyang.net/cars/ferrari.html?ferrari248.htm

Tom
fest
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slippery subject

Post by fest »

I was wondering about Engine Oil:
Manual(s) state use 10W-50
but hard to find
I substituted 20W-50
with the following rationale

Manual shows that viscosity
suitable for temp range down to 5°F:
as I will not drive of start the car
when it is that cold (32°F minimum)
20W should be OK

other than that
the dange with stiffer oil
is that the oil cooler can burst
upon first start up
from over pressure
if too heavy oil is used:
should not be a prob
as the oil bypasses the cooler until hot (thermostat)

any sage words of wisdom?
is it worth (necesary) hunting down the 10W50?
(have not found any locally)
I have just been topping it off
I would like a final determination
by the time I have to change it
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tyang
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Post by tyang »

Hi Fest,

I would worry more about the oil filter bursting before the oil cooler. I've seen this happen on three cars when starting in the winter. A no-name filter split at the case, and a Fram and a Bladwin sprayed oil out from the seal when the gasket failed. These filters are supposed to withstand a certain amount of pressure, but who knows what exactly happend. If you're going to drive your car in cold weather, it might make sense to use a lighter oil for winter months, but switch to the heavier oil in summer, but definitely keep and eye on your oil pressure when starting your car!!!

Tom
fest
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Joined: Mon Mar 03, 2003 10:59 pm

delco in a ferrari?

Post by fest »

found this list of 10W-50 availability

http://eolcs.api.org/FindBrandByViscosi ... ity=10W-50
Michael Bayer
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Joined: Mon Nov 04, 2002 7:22 am

Post by Michael Bayer »

Thanks Tom, will put the 250 in! Again, sorry I couldn't make you Pebble Beach gathering, for sure next year!
JimB
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Location: San Jose, CA

Post by JimB »

I too bought the Penright oil but chose not to use it after careful consideration. It is not appropriate for limited slip differentials. It is what they call steam oil and is really more appropriate for the chains on horseless carriages. Instead I used Redline high impact oil for the differential. This is a full synthetic and has all the additives for limited slips and has a viscosity of about 140. It is very satisfactory. Go to redline.com and you can look at all their oils.

Jim Burnett
fest
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newer diff

Post by fest »

so what's to use in the 'later' Diffs
(I have 400i)
with indepenant rear suspension, posi, etc

Manual sez: 80W-90
is this 'off the shelf'

should I put in 'Limited Slip' Additive
(like from GM, Red Line?)

recommendations?
fest
Posts: 415
Joined: Mon Mar 03, 2003 10:59 pm

mobil the one

Post by fest »

found this stuff:

http://www.mobil.com/USA-English/Lubes/ ... 80W-90.asp

sounds pretty good...
of course, they are the ones selling it ;)

I am a big fan of Mobil 1
(and use exclusively it in my late model commuter)
so, I should have no qualms about selecting their Gear lube, either
JimB
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Location: San Jose, CA

Post by JimB »

Modern differential oils will have a limited slip additive in them. Look for a GL5 rating. Mobil 1 is great stuff. The 330 gt's have spiral bevel gears in the differential and later cars have Hypoid gears. You must use oil for hypoid differentials if that is what you have. It does not make a difference if you have a spiral bevel diff.

Jim Burnett
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tyang
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Post by tyang »

Jim's onto a good point. Hypoid gears work differently than regular spiral cut gears. From I research, hypoid gears do not intesect the crown gear in the middle (think of the crown gear as an "O") kind of like this: O- , but instead mesh with the crown gear lower down like this: O_ This offset give more clearance inside the car so the center tunnel is not as high, but there is more of a slipping action between the gears to make this happen. This added friction requires a special gear lube. That's why you see "hypoid gear oil."

My diff is a regular spiral cut, non limited slip rear, so it can use the heavier oil. If you have a hypoid, or limited slip, I would use something else.

Another piece of useless information that the rest of the world couldn't care less about!

Tom
JimB
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Location: San Jose, CA

Post by JimB »

Not useless info at all Tom. You are spot on correct.

Jim Burnett
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