Low sulfur diesel shrinks seals

Here's a technical bulletin put out by Chevron about how the new low sulfur diesel blends are causing fuel leaks in older vehicles. The new fuel mix causes the old stiff seals on these cars to shrink and leak.

http://www.chevron.com/products/prodserv/fuels/diesel/documents/elastomer_chevron_tb_2005Aug.pdf

Interestingly enough another article that I read but can't find right now stated that fleet managers in California were blending bio-diesel with the ultra low sulfur fossil fuels to offset this shrinkage. They're doing this because bio-diesel and vegi oil cause the opposite behavior in seals, making them expand.

Now, I'm not absolutely sure about this, but my 84 wagon was a bit of a smoker on start-up. After converting it and running two tanks of vegi oil, I've noticed that it's stopped smoking. No more James Bond, even on cold start accelerations. I'm assuming this is because the vegi oil caused seals in the system to swell and reduce leakage. I'm also assuming that the seals that swelled were the valve stem seals. There could be some seals in the injector pump, but I don't know anything about the insides of that thing.

I'll try to find that article on mixing blends.