[6pack] Rotella T CJ-4

[Ed McGuirk]

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Date: Tue, 11 Mar 2008 16:02:10 +0000
From: im sloane <im_sloane at hotmail.com>
Subject: Re: [6pack] Rotella T CJ-4

I've always been a Castrol 20W50 guy and tend to resist change.

This 'zinc' topic has been interesting, but somewhat over my head. Could
someone give a brief explanation of this and the pros/cons of making a switch
to Rotella?

Sloane  :) 
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In the simplest terms as I understand it. (please correct me where I am wrong)

1 Zinc is good for engines.
2 Zinc is bad for catalytic converters.
3 API improves engine oil specification every so often. Spark engine oil recently went from an API-SL to API-SM rating. I think compression engine oil (Diesel) ratings are up to CI.
4 The latest API-SM rating calls for vastly reduced Zinc. (synthetic or not - no zinc if you see "SM")

My guesses from what I have read on the internet:

5 Racing oils (many 20-50 oils), Motorcycle oils, and Diesel oils still have zinc.
6 The change from API-SL to API-SM is probably why you rarely see oils that carry both "S" and "C" ratings anymore.

(I won't even get into the whole group 3 / group 4 synthetic oil brouhaha that allows most oil companies to brand dino oil as "synthetic")

I am not an oil expert.
ed