Re: Mobil 1 vs. Valvoline?

Interesting topic..........
Ok, here's a question on synthetics from another angle.
Is there any evidence that synthetic lubricants, specifically synthetic gear lubes (80W90, etc), do not play well with RTV
(silicone) sealants? I've read that some synthetic lubes will chemically atack RTV sealant.
I know this is true of some petroleum distillates (used as solvents) and more specifically gasoline, but I thought RTV was not only safe, but intended for things like differential and valve cover gaskets.
Now I gotta wonder about motor oils too......
Not Dead Yet
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Slick 50 once took a really well running engine and made a complete pig out of it. The problems started with slick 50 and just went from bad to worse. Slick 50 clogs and gunks up your oiling system! Do NOT use it.
I repeat, do NOT use it.
wrote:

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On Tue, 21 Sep 2004 19:23:20 -0500, NotDeadYet

What I had heard (accurate or not) is that Synthetics do not cause the seals to swell. Thus if used exclusively the seals may leak & to remedy the situation Dino oil is required to swell the seals back into shape.
Not saying that it's true. Just what I heard.
I'm too cheap to save money the synthetic way so regard all my synthetic/dino oil conversations in this light.
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wrote:

That the use of synthetics caused problems with seals may be just folklore. At least now all synthetics include "seal Swellers"
Conventional oil is satisfactory for most users. I just think they are worth the tiny extra cost especially if you work your engine hard like pulling heavy loads in mountains or on the desert. And of course if you keep your vehicles for a long time. Most trade their vehicles off long before the engine wears out even when using conventional oils.
Some users claim their gas mileage increases enough to more than pay for the difference. That is hard to prove. I come up with something like a half mile per gallon is all that is necessary to make up the cost. Another attibute is that synthetics do not thin out as much so they do not need to use Viscosity Improvers (VI). Those additives caused major problems in many engines, especially when 10W40 was used. I view a synthetic such as 5W30 as being similar to a straight 30 weight oil except it does not get as thick when cold. Conventional oils has to have VI to keep from getting too thick.
There are several good web sites about oils:
http://www.nightrider.com/biketech/oilinfo1.htm
http://www.chris-longhurst.com/carbibles/index.html?menu.html&engineoil_bible.html
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Try some Synthetic in an oilcan, you'll be reaching for " that " can exclusively. Works good in car motors too. Don't use it in small engines, it's too thin, and cleans too well, if you have a leak, it will find it !
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I disagree. It works great in air cooled engines. I have used nothing but 5W30 synthetic in my mowers and snow blowers for several years. Since it doesn't get as thick when cold they start much easier. When hot it is the same or thicker than straight weight 30. Remember that cold 5W30 has a greater viscosity than hot 5W30. (all oils thin as they get hot - Synthetics don't thin as much so they don't need Viscosity Improvers).
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