Switching to synthetic

speedmetal6.6

Dodge Destroyer
Nov 3, 2008
252
0
0
Gillette,Wyoming
Ive used a few different oils , and im currently running Castrol tech extreme 15-40. I orderd some Amsoil 5-40 but was told it would ruin my seals and leak? Is this true or will I be ok?
 

BlkMax

Member
Sep 1, 2008
743
4
18
Wasilla, AK
I does not ruin the seals, but if the seals are worn or weak, you may experience oil "leaks" because the synthetic oil is better able to flow through the imperfections in the older seals.

It just depends on the individual engine. I have run Rotella T 5w40 full synthetic in my Duramax for years with great results and no leaks. I put the Rotella in my fathers 6.0 gasser and in 3000 miles he was 3 quarts low with no apparent oil leaks. The engine was consuming the oil...I would guess through the valve guides. He put dino oil back in instead of the synthetic and is back to being about 1 quart low in 5k miles.

In extreme cold conditions, I think these synthetic oil "leaks" are seen more often because of the loss of elasticity in the seals when cold.

Just my $0.02
 

MACKIN

Smell My Finger...
Aug 14, 2006
3,948
1
0
Connecticut
Do you think that that is really true about being able to leak more so ,synthetic, over conventional? I went to one of those Quicky lube places with one of my crashers as I didn't have the time to do it myself and a lube Jockey told me the same thing. I just gave him the stink eye like OK what-ever!

I myself don't see it 5w is 5w synthetic is a better long lasting lubricant I just don't see how it will slip through the cracks easier. All oil when cold has a different pour characteristic. Is there any real proof,doubting Thomas here?
 

BlkMax

Member
Sep 1, 2008
743
4
18
Wasilla, AK
Do you think that that is really true about being able to leak more so ,synthetic, over conventional? I went to one of those Quicky lube places with one of my crashers as I didn't have the time to do it myself and a lube Jockey told me the same thing. I just gave him the stink eye like OK what-ever!

I myself don't see it 5w is 5w synthetic is a better long lasting lubricant I just don't see how it will slip through the cracks easier. All oil when cold has a different pour characteristic. Is there any real proof,doubting Thomas here?

I know that when synthetic is placed in an engine that has run dino for a long time there is a chance that oil will be consumed at an alarming rate with no apparent external leaks. I saw this with my fathers 6.0 gasser. I think he had about 135k when we tried to make the switch.

It would also make sense to me that there would be a chance for older seals to not be able to contain an oil that is more slippery. I agree, 5w is 5w, but there is a difference in pour point temperature between oils with the same weight. I'm not saying the seals are damaged by the synthetic, simply that older seals that have wear may not be able to contain synthetic where they would still be able to contain a dino oil. I have also seen SBC's that were switched develop valve cover gasket leaks with the synthetic where there was no visible leak with the dino. We changed the valve cover gaskets and no more issues.

I'm not trying to frighten anyone off here, just saying what I have seen, in specific cases.

FWIW, I love the synthetics, and run them in everything I have except a HIGH miles '97 Suburban I bought well used for the kids. The sub and dad's truck get dino.
 

paint94979

Beer Nazi
Sep 18, 2006
11,715
8
38
37
At 32k miles I swapped to synthetic, leak at PS valve cover started, front diff, and ps rear axle seal. Coincidence? I doubt it.
 

MACKIN

Smell My Finger...
Aug 14, 2006
3,948
1
0
Connecticut
I just wondered like I said and IMO if synthetic leaks there is probably a leak already and in theory maybe it looks worse or is worse with synthetic.

The pour theory is correct , I made mention of that myself. I guess I'll look at it in the Hydraulic verses a air cylinder. You might see a drip but you will hear a air leak better! :D

Your probably correct like I said I heard it from a Oil Jockey for the first time and you know what kind of info they pass along. I run synthetic in my Dually no consumption and no leaks to speak of.
 

speedmetal6.6

Dodge Destroyer
Nov 3, 2008
252
0
0
Gillette,Wyoming
So would you guys switch or not? Im just looking for advice. I was hoping to save some $ through less oil changes and I heard it was better for the engine. If its gonna cause problems and possibly ruin sh@t I wont use it
 

MACKIN

Smell My Finger...
Aug 14, 2006
3,948
1
0
Connecticut
I would with out hesitation. Not sure about Amsoil but if thats the brand you chose just not my choice I'd stick to main stream brands. Many use Amsoil
 

blk smoke lb7

<-----Lots of green $
Nov 8, 2010
5,694
0
36
57
belvidere,ill
Syn oil wont ruin anything but i did switch our 99 yukon over to mobil1 with 140,000 when we bought it and the rear main started leaking before i sold it i switched it back to regular oil and the oil leak all but stoped,but on the flip side i think its great for the motor and i did see about 1 miles per gallon better.
 
Good discussion. All points are things to consider. Agreed that switching will not cause harm but may uncover some unseen problems. The higher the miles on the engines, the increases change of things you may see. I've had vehicles that don't use a drop and I've had vehicles that use a qt as much as 1/1500 miles. (This was in a vehicle known for usage, but it was worse with synthetic).
If you try it and it doesn't work out the way you want it to, there is no harm in going back. It the truck has been well maintained since new and it's not using or leaking anything now, I don't think you'll have any troubles.
 

CurtisEmery

New member
Mar 21, 2008
486
0
0
Ontario, Canada
There is something in the mineral oils that help swell the seals. This was touched upon in my lube training for Schaeffers oil. I believe it has to do with the additive package specific to the mineral oils. Don't think it has anything to do with a synthetics abilty to flow better than mineral oil in colder temps anything like that.
 
All lubricants have to have an additive package that addresses seals. Here is a little piece on that subject:

Elastomer Compatibility
Elastomer/seal compability of a lubricang fluid is extremely important in
ensuring proper equipment operation. Common problems that can result
from seal/oil incompatability is the degradation, shrinking or swelling of the
seals.

AMSOIL Advantage


Seal compatability and seal conditioning is an important characteristic of
a lubricant’s formulation. AMSOIL lubricants condition seals, maintaining
their ability to function correctly by inhibiting contaminant penetration at
the seal. Because seal materials are sensitive to thermal conditions, the
inherent thermal control of AMSOIL synthetic lubricants promotes seal life
and integrity.
 

Kartmnn

New member
Oct 27, 2011
244
0
0
East Providence RI
Ben said that regular old oil is fine. I asked him about switching to syn., and he said that it just prolongs the oil change timetable by alittle. I buy Rotella T 15w-40 at walmart and a filter for less then $40.