20w50 blows rear main seals out ?

[stilbo]

I ran 20w50 for about 15k miles... highway speeds (65-80mph)@ 55 - 85 degrees ambient on my '93 XLT... rear main started leaking about 5k miles ago.

Tonight I changed to 5-30 as per Ford .....

Pressure gauge shows 20% reduction in indicated pressure.....

Anybody think there's a correlation between leaky seal and 20w50?

Thanx..

RD

 

[stilbo]

Anybody have ANY input here?

With all the posts re: 5w30, I'd have thought there woulda been somebody out here that could help.....

 

[ok89]

 

[Lemondrop]

20w50 is thicker than 5w30 . In my experience thicker oil leaks out of main selas less than thinner oils . Ive had engines that leaked oild and tossed in 20w50 or straight 40w and the leaks slowed for a little while . The extra pressure from the thicker oil could cause more oil in the are of the rear seal but if it leaks with the thicker oil it will leak with the thinner . Only way it won't is if the rear seal had a piece of trash get into it that slung out but Ive never seen that before .

 

[JDraper]

Lemondrop is correct. Running a heavier oil usually means less leakage and higher pressure. If you are leaking with 20w50, you will probably leak quite a bit more with 5w30. The oil weight will have nothing to do with a leaky rear main seal. The rear main seal just keeps oil from seeping out around the crankshaft, and is not under any oil pressure, per se.

FYI, here is what the oil weights mean (This is from memory, so someone slap me down if I'm wrong :mattmoon: ): The first # is the viscosity of the oil, and the second # is the viscosity it protects like. The lower the first #, the thinner the oil. For example, 5W30 is a 5 weight oil that protects as well as a straight 30 weight oil. A 10W30 oil is a 10 weight oil that protects as well as a straight 30 weight. The oils are formulated differently to produce the different protection levels.

 

[ok89]

JDraper- here is a good oil website
Dead Link Removed

 

[mdrut]

The number one cause of blowen seals is over filling....The thicker oil will leak less, and increase pressure..BUT...Thicker is not always better, in a new or low mileage engine, the thicker oil will NOT cover the bearing as well as the thinner oil. The way that todays engines are designed, they call for lower tolerances..The "tighter" engine requires an oil that will fill the "gap" between bearing and journal, hense the need for lighter weight oils. Unless you are running a very high mileage motor, or an older, PRE- 1980 engine, use the lighter oil. AND NEVER OVER FILL..
The front and rear seal get blowen by the extra amount of oil "slapping" against the seal during acceleration and brakeing...
Good Luck...BTW, the rear and front axle seals will be effected the same way by over filling.

 

[sod40sport]

If you go with too thick of oil your acctually robbing yourself horsepower, and hurting your engine. I wouldnt go above 10w 40, but hey thats just me

 

[EliteConcept]

my dad put 20w-50 in his 69 camaro....he said its for high high preformace engines...or muscle cars....not explorers or regular cars

 

[stilbo]

Thanx..

Thanx guys....

Whe the differential overfills were mentioned, I got to thinkin (dangerous) about the lube place that loosened the oil filter bracket on my Xr4Ti and I wound up buying a new turbo and then another one must have forced a qaurt too much hypoid into my front dif last winter cause it blasted out a new seal.

I've notied that when these guys at the oil change places fill the crankcase, they use a bulk dispenser and don't quite get the amount right. Seems like they over fill but I've never seen it more than 1/16" over the full mark. In an International 4700 diesel that's about a gallon too much but the Plory it didn't seem like it'd matter...

Anybody know what the going labor charges are for pulling the transfercase and transmission on a 4wd '93 XLT?

Maybe if I have the rear main seal replaced, it might be a good time to service the trans front seal and bushing and all the little trans seals and gaskets too?

Thanks again.......

SUX though......

I't supposed to snow by week's end and I don't want to get the '97 or the Probe GT slimy....



Dr Ron

 

[EliteConcept]

hey stilbo
where are you from??


I am also from NW indiana,
I live in the michigan city area...

 

[Robert]

Originally posted by JDraper
...
FYI, here is what the oil weights mean (This is from memory, so someone slap me down if I'm wrong :mattmoon: ): The first # is the viscosity of the oil, and the second # is the viscosity it protects like. The lower the first #, the thinner the oil. For example, 5W30 is a 5 weight oil that protects as well as a straight 30 weight oil. A 10W30 oil is a 10 weight oil that protects as well as a straight 30 weight. The oils are formulated differently to produce the different protection levels.

The first number is the viscosity at 0 degrees C, the second number is the viscosity at 100 degrees C. A 5W30 has a viscosity of 5 centistokes at 0 C and 30 centistokes at 100 C. The lower the number, the thinner the oil.