Switching to synthetic
#21
Registered User
#22
Registered User
It's not synthetic that was the problem, it's GL-5 instead of GL-4. Red Line MT-90 & Amsoil MTG are both the bees knees for smooth shifting and they're both synthetic.
#25
Registered User
Join Date: Jun 2009
Location: Corona, CA
Posts: 153
Likes: 0
Received 0 Likes
on
0 Posts
I switched to synthetic for the diffs, tranny and transfer case in my '87 with 270,000 miles. Before the switch I had zero leaks, now both diffs leak.
If I had used dino oil would they have started leaking after the oil change? Did the synthetic cause the leaks? I don't feel qualified to definitively answer yes or no, but I can offer my personal story for whatever it's worth.
If I had used dino oil would they have started leaking after the oil change? Did the synthetic cause the leaks? I don't feel qualified to definitively answer yes or no, but I can offer my personal story for whatever it's worth.
#26
Registered User
iTrader: (1)
I switched to synthetic for the diffs, tranny and transfer case in my '87 with 270,000 miles. Before the switch I had zero leaks, now both diffs leak.
If I had used dino oil would they have started leaking after the oil change? Did the synthetic cause the leaks? I don't feel qualified to definitively answer yes or no, but I can offer my personal story for whatever it's worth.
If I had used dino oil would they have started leaking after the oil change? Did the synthetic cause the leaks? I don't feel qualified to definitively answer yes or no, but I can offer my personal story for whatever it's worth.
#27
Registered User
There is also Class III, which is a highly refined petroleum based oil that is superior to straight dino but lacks the some of the advantages of the full syn Class IVs & Vs. Those include Castrol Syntec, Pennzoil Platinum and Valvoline SynPower. Mobil 1 used to be a straight PAO, now it contains Group III oil, and they won't say how much, so best guess is more than 50%. Castrol Edge is likewise a blend that contains Group IIIs.
This is from Millers Oils, a Brit lubricant manufacturer established in 1887:
The high molecular polarity of esters when combined with PAO can
also enhance the ability of the engine lubricant to soften or dissolve
engine deposits improving internal engine cleanliness. Finally the
seal swell characteristics of the ester can be used to counteract the
propensity of PAO products to attack and harden elastomers in the
engine.
Early full synthetic PAO/ester blends often introduced crankshaft
oil seal leaks after a short period of use following an oil change.
Replacing a mineral oil with one of these new oils caused the
crankshaft oil seals, which had swollen as a result of chemical action
from the Group I product, to shrink and harden through an inadequate
balance of PAO and ester. Increasing the amount of ester and re-
balancing the formulation quickly solved the issues and although
anecdotal stories still abound, full synthetic lubricant formulations no
longer have sealing issues.
also enhance the ability of the engine lubricant to soften or dissolve
engine deposits improving internal engine cleanliness. Finally the
seal swell characteristics of the ester can be used to counteract the
propensity of PAO products to attack and harden elastomers in the
engine.
Early full synthetic PAO/ester blends often introduced crankshaft
oil seal leaks after a short period of use following an oil change.
Replacing a mineral oil with one of these new oils caused the
crankshaft oil seals, which had swollen as a result of chemical action
from the Group I product, to shrink and harden through an inadequate
balance of PAO and ester. Increasing the amount of ester and re-
balancing the formulation quickly solved the issues and although
anecdotal stories still abound, full synthetic lubricant formulations no
longer have sealing issues.
PAOs were first synthesized in 1937, but the first major development and use of synthetic oil was of ester-based aircraft engine oils by the Nazis, partly because of constrained supply of mineral oils but also because the synthetic oils flowed better at cold temperatures and didn't break down so much when hot. Americans and Brits began using ester-based oils in military aircraft shortly after WW II and they are widely used in conventional and jet aircraft engines today.
Chevron actually had a line of PAO-based engine oils in the mid sixties, Red Line began selling ester-based oils in 71, Amsoil (then Amzoil) began selling repackaged Hatco diester-based oil in 72, but it was with the introduction of the PAO-based Mobil 1 in 74 - right in the midst of the Oil Crisis caused by the OPEC Oil Embargo - that synthetic oil really began to be used in automobiles.
http://en.wikipedia.org/wiki/Synthetic_oil
http://www.amsoil.com/articlespr/historyarticle.aspx
http://www.diolube.com/ESTERS%20IN%2...LUBRICANTS.htm
http://www.bobistheoilguy.com/forums...Number=1175204 (lots of good info further down in thread)
I do agree with the suggestion that synthetics are more useful in very cold temps than warmer ones, and that a good mineral or group III oil can provide plenty of protection if changed often enough.
#30
Registered User
You can still get dino GL-4 gear oil at Napa under the Sta-lube label.
Last edited by flyingbrass; 11-07-2009 at 03:41 PM.
#31
Registered User
Since synthetic cleans out the crud better (apparently because of the esters it contains, not stronger detergents), would running it occasionally, say every x oil change, help keep an engine cleaner with no detrimental effects on seals? Is exposing seals to esters without continuing to use ester-containing oil detrimental in any way? If there's no problem, synthetic would seem to be a good way of doing a mild "flush" on occasion.
#32
Registered User
I meant switching to synthetic on a high mileage engine after using dino oil exclusively before. But, you raise a good question.
Since synthetic cleans out the crud better (apparently because of the esters it contains, not stronger detergents), would running it occasionally, say every x oil change, help keep an engine cleaner with no detrimental effects on seals? Is exposing seals to esters without continuing to use ester-containing oil detrimental in any way? If there's no problem, synthetic would seem to be a good way of doing a mild "flush" on occasion.
Since synthetic cleans out the crud better (apparently because of the esters it contains, not stronger detergents), would running it occasionally, say every x oil change, help keep an engine cleaner with no detrimental effects on seals? Is exposing seals to esters without continuing to use ester-containing oil detrimental in any way? If there's no problem, synthetic would seem to be a good way of doing a mild "flush" on occasion.
#34
Registered User
My understanding is, and i checked it out, is that you can use a 75/25 dino/syn mix, same weight with no prob. And is that not what Syntec is? a partial mix.
#35
Registered User
Informative forum! personally Im using Mobil One high mileage.I will use it for the rest of the life of my engine.Just 5 days ago put Mobil 1 synthetic 75/90 in rear diff.Going to do same to Tcase and front diff. in 2 weeks.Gets kinda cold here in Colorado.Its all about choice,Im trying to prolong engine life.I dont have 5 Gs for a new motor,lol.
#39
Registered User
Castrol does also sell a "Syntec Blend" - which is a blend of group III Syntec with conventional dino oil (probably their GTX product). I've read that synthetic blends contain 30% or less synthetic, but I've no idea if that's true. Anyway, a group III is not a "true synthetic", but offers some of their advantages at a lower price.
Since synthetic cleans out the crud better (apparently because of the esters it contains, not stronger detergents), would running it occasionally, say every x oil change, help keep an engine cleaner with no detrimental effects on seals? Is exposing seals to esters without continuing to use ester-containing oil detrimental in any way? If there's no problem, synthetic would seem to be a good way of doing a mild "flush" on occasion.
BTW, esters aren't just found in synthetic oils; they're used in high-mileage oils - even the dino ones - to give those oils their seal-swelling properties.
I can't remember who it was I talked to, might have been one of the guys at Napa, that said he runs one quart of synthetic with the rest of the dino oil when he does an oil change. He said he's done it for years to get the cleaning properties of a little synthetic and the cost savings of dino. After reading all the posts about syn/dino and some other research I think that might be the way to go.
An alternative is to use a group III. The oil-obsessed guys over on bobistheoilguy are pretty high on Pennzoil Platinum, which is a group III. I've used Syntec for 14 years and when I changed the head gaskets at 218k miles, the cyl walls were in great shape with the cross-hatching still intact. My change intervals have been 5-6k. Valvoline SynPower is another good group III. Castrol Edge is currently Castrol's premium synthetic; I think it contains some PAO together with group III oil. In Canada, Petro Canada's group IIIs are so well refined they apparently have cold temperature flow characteristics quite similar to the group IVs & Vs and they are called by some "Group III+".
http://lubricants.petro-canada.ca/re...2E&language=en
EDIT: In re-reading your post, Junkers, I see you were looking to blend in the synthetic to get the cleaning action, not necessarily the cold flow or long service benefits. If the chemistries were compatible, I think that might work, depending on the synthetic chosen. IDK if PAOs clean as well as the esters do (Amsoil's cleaning properties might be due to the esters it contains). I do know that Syntec does not clean as well as the group IVs or Vs. After 111k miles of Syntec, my engine was not gunked up and was fairly clean, but it wasn't totally aluminum colored, either - it was a little bit varnished.
Last edited by sb5walker; 11-07-2009 at 09:21 PM.
#40
Registered User
I've switched all my cars over to synthetic with zero issues. Synthetic is always a better choice, IMO. If your truck develops leaks due to the better detergents in synthetic, replace the seals and be done with it.
Then send your oil sample to Blackstone Labs for analysis. I change my oil about every 9k miles, with a filter swap at 4.5k. I could go a little longer, but I don't bother.
Then send your oil sample to Blackstone Labs for analysis. I change my oil about every 9k miles, with a filter swap at 4.5k. I could go a little longer, but I don't bother.