do syn blends swell seals like dinos?

[Ray H]

Group III base stocks, being almost devoid of aromatics, and Group IV base stocks being virtually free of aromatics, do not promote seal pliability and dimensional stability. However, when formulated with Group II as a synthetic blend, there's probably no danger of seal shrinkage. Certain esters promote seal swell and have been used as an additive for that purpose, too.

 

[sky jumper]

question - do syn blends like Motocraft 5W30 have the same seal and gasket conditioning properties as straight dino? I forget exactly what it is about dino that keeps seals and gaskets oil tight (I read a post a while back about aromatic solvents or something??).

 

[Dick in Falls Church]

To the best of my knowledge, all the oil on the market today, at least the brand name stuff, is blended to provide a slight seal swell (enough to compensate for wear).

 

[John_E]

quote:

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Originally posted by Ray H:
Group III base stocks, being almost devoid of aromatics, and Group IV base stocks being virtually free of aromatics, do not promote seal pliability and dimensional stability. However, when formulated with Group II as a synthetic blend, there's probably no danger of seal shrinkage. Certain esters promote seal swell and have been used as an additive for that purpose, too.

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Does this mean that I should add a little dino to each Mobil 1 crankcase fill in my 1.8T? I would not want to add more than 1/2 qt. out of the 4-qt. capacity, due to turbo-coking concerns. I have no idea whether this is mere concindence, but my cam seal problems started when I got the infamous "sludge notice" from VWoA and switched from dino to synthetic oil. I do not want to have to pay for a cam seal replacement out of warranty.

 

[Ray H]

Uh, Isn't Mobil 1 formulated with esters?

 

[jonny-b]

John_E. You can also go the other way, and use a maintenance dose of Auto-Rx. Besides swelling the seals it also cleans better than the esters in Mobil1. This will ensure your engine being clean inside and because of this, the oil will perform better in protecting your engine. The 1.8 turbo from VW can be hard on oil, so this will give you a very good protection.

 

[John_E]

quote:

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Originally posted by jonny-b:
John_E. You can also go the other way, and use a maintenance dose of Auto-Rx. Besides swelling the seals it also cleans better than the esters in Mobil1. This will ensure your engine being clean inside and because of this, the oil will perform better in protecting your engine. The 1.8 turbo from VW can be hard on oil, so this will give you a very good protection.

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Thanks for the post, Jonny-b. I have a spare bottle of Auto-RX and have considered doing precisely what you suggest, but I wasn't sure whether it would do any good.