Problems with using heavier wt oil

[yummy88]

My 1991 LS 400 is recommended to run 5-30 oil. It has 200K miles and has a bit of rear main seal leak and I believe it is using oil (not sure if it is from the leak.

Anyway, I plan to use Rotella 20-50 to reduce engine noise, oil consumption and hopefully reduce the leak from rear main seal.

What are the ill effects from using a much heavier oil. I would imgaine that oil pressure would be higher and if so would that force more oil out of the rear main seal.

In the past I usually use 10-40 but when I switched to 5-30 that that was when it started leaking. I have since switched back to 10-40 and lthe leak has slowed so I thought why not just switch to 20-50 and hopefully the leak might stop.

 

[Shannow]

Oil pressure isn't directed at seals (there's usually a slinger or deflector to stop the squeeze film being jetted at a seal).

 

[Merkava_4]

I'm thinking 10W-40 Maxlife is your oil.

 

[Camu Mahubah]

I'll second the Maxlife. Try 10w30 first, then 10w40. No need to go higher than 10w40.

 

[TallPaul]

30wt to 50wt is about doubling the thickness (11 cSt to 20 cSt). Pretty extreme. Try 10w40 first (about 14 cSt).

How much consumption? If you are only adding a quart in 3000 miles I would not worry about it. Just top up.

Get an oil pressure gauge and see how it compares to spec. If significantly lower on 30 wt, try 40 wt.

Maxlife or other HM oil would be good choice given main seal seep/leak.

 

[VK56VD]

I would stick with the recommended factory weight as it will give you the best performance and fuel economy. Have whatever is leaking fixed to resolve the problem or just keep adding oil when needed to maintain proper level. Give MaxLife a try as others have suggested in the 5w30 weight.

Also, you may consider giving Auto-RX a try to restore engine compression and clean up your seals.

 

[bigjeffie]

i will 2nd the auto-rx suggestion.
i was quite a cynic.
did wonders for my rav4.

 

[yummy88]

It has Auto-RX in it right now with some bulk 10-40 oil in it. However I already bought 5 quarts of 20-50 Rotella oil and it would be a waste if I do not use it.

So perhaps I will use this Rotella 20-50 for the rinse cycle. What do you guys think about running Rotella (dino oil) 20-50 for about 3K miles. Will there be any permanent damage? Fuel consumption is not a problem because I avg only about 20 miles a day. Cold start is not an issue because I live in SF Bay Area and the lowest be get here is 45F at this time of the year.

 

[VK56VD]

If you still have the receipt, I would exchange it for a proper weight oil. Most stores will give you store credit if you've thrown away your receipt and let you exchange your oil to the proper weight.

I would do whatever I could to not use the 20w-50 if I was the owner of your vehicle.

 

[PT1]

Originally Posted By: Camu Mahubah
I'll second the Maxlife. Try 10w30 first, then 10w40. No need to go higher than 10w40.


I third the Maxlife

 

[Bulli]

mix the 20-50 with some 10-30 or 5-30

 

[Rock_Hudstone]

Originally Posted By: yummy88
Anyway, I plan to use Rotella 20-50 to reduce engine noise, oil consumption and hopefully reduce the leak from rear main seal.

Rotella is not produced in a 20w-50 weight that I'm aware of.

However, Rotella 15w40 is widely available and it certainly couldn't hurt to give it a try on high mileage engine like yours. It should at least improve the engine noise.

 

[Gregory]

I'd have no problems using 20w-50.

 

[yummy88]

Rock

You are right it IS 15-40 (I had been buying individual quart bottles of 20-50 for top ups between service and was confused).

Went ahead with the Rotella and so far so good.



Originally Posted By: Rock_Hudstone
Originally Posted By: yummy88
Anyway, I plan to use Rotella 20-50 to reduce engine noise, oil consumption and hopefully reduce the leak from rear main seal.

Rotella is not produced in a 20w-50 weight that I'm aware of.

However, Rotella 15w40 is widely available and it certainly couldn't hurt to give it a try on high mileage engine like yours. It should at least improve the engine noise.

 

[Oilgal]

Do you guys think it is more safe generally, to go outside of OEM viscosity recommendations, by going thicker or by going thinner?

I realize of course that it depends on how much in either case though.

I would just like to hear your thoughts about this.

 

[Merkava_4]

Originally Posted By: Oilgal
Do you guys think it is more safe generally, to go outside of OEM viscosity recommendations, by going thicker or by going thinner?


I was wondering when someone would ask that question.

My two cars are both mandated to use 10W-30. I would have no fear of going to 10W-40, but I'm very fearful of using 5W-20 in my cars; therefore, it will never happen.

 

[VK56VD]

Originally Posted By: Oilgal
Do you guys think it is more safe generally, to go outside of OEM viscosity recommendations, by going thicker or by going thinner?

I realize of course that it depends on how much in either case though.

I would just like to hear your thoughts about this.


Oilgal-

Are you still trying to figure out the article by Dr. Haas on oil viscosity?

 

[Oilgal]

Originally Posted By: Merkava_4
Originally Posted By: Oilgal
Do you guys think it is more safe generally, to go outside of OEM viscosity recommendations, by going thicker or by going thinner?


I was wondering when someone would ask that question.

My two cars are both mandated to use 10W-30. I would have no fear of going to 10W-40, but I'm very fearful of using 5W-20 in my cars; therefore, it will never happen.



After reading those articles, JAG link to, I am inclined to stay with the OEM recommendation myself now. There is lot more to this than I presently understand, and so I am going to stay with the OEM recommended 5w 30, until I know better. So we are talking years then.

 

[Oilgal]

Originally Posted By: Spartuss
Originally Posted By: Oilgal
Do you guys think it is more safe generally, to go outside of OEM viscosity recommendations, by going thicker or by going thinner?

I realize of course that it depends on how much in either case though.

I would just like to hear your thoughts about this.


Oilgal-

Are you still trying to figure out the article by Dr. Haas on oil viscosity?



Who me? Well, yeah, I can't help it. I find all of this fascinating for some reason. I think Dr. Haas is onto something. I am just not well informed enough to try it on my engine. Between Dr. Haas and those linked articles JAG gave me, I am now to the point that I realize, I am a complete blithering idiot oil and mechanical wise. be-deep-ba-dee

So I am at a good stating point.

 

[mjoekingz28]

you're very wise oilgal.

"I am just not well informed enough to try it on my engine."


I see the owner's manual like I do speed limits. They are a great baseline and should be followed if you don't know the ropes. But once you learn what you're doing and what to expect, you can stir things up a bit.