Are all 5W20's synthetic or blended?

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Mar 7, 2004
Southwestern Ontario
Are all 5W20 motor oils a synthetic or synthetic blend? They cost slightly more than conventional oils, but they do not say synth or semi-synth on the packaging. Why not?
Any 5w20 that meets Ford's spec (which requires a double length Sequence IIIF test) will have to have some Group III in it. Johnny has posted that Pennzoil's 5w20 is 40% Group III. Since most 100% synthetic oils sold at retail are Group III based, companies could call their 5w20s a "synthetic blend" if they label their Group III oils "full synthetic." Most choose not to, however.
Darn, I was thinking of throwing in some 5w20 into my high mileage aspire to see how well it did, but I was going to do this during my AutoRX rinse phase.
I plan on sending samples of Castrol GTX and Syntec Blend 5w-20 to Blackstone for VOA results. I know this won't tell me "synthetic" percentages, but it will at least let me know how similar their additive packages are. Now that Castrol has Syntec available in 5w-20, I'd like to know exactly where the Syntec Blend falls (percentage-wise) in the scheme of things if even the plain jane GTX has some synthetic in it. Z-
Originally posted by crimsontide: which 5w20 or 0w20 oil has the most group 3 oil in it.....pennzoil @40%?
There is no way to know for sure (other than having someone on the "inside" like Johnny with Pennzoil). Amsoil's 5w20 is all Group III. Mobil 1 0w20 is all PAO. In general, I'd say that any "conventional" 5w20 is going to have between 20% and 50% Group III in it.
Originally posted by 03HD: So Pennzoil's 5w20 meets fords 5w20 syn-blend specs?
Yes Pennzoil 5w20 meets the Ford spec, and syn blend has nothing to do with it. Ford doesn't dictate how the oil is made, they just set down the performance criteria and it's up to the oil companies to build an oil that meets it. The Ford spec in question is WSS-M2C153-H.
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