[JMJNet]

I suspect, due to the current spec requirement, most oil will become syn blend or semi synthetic.

There are a lot of "untrue old wives tale" on synthetic oil.

 

[JMJNet]

Does anyone make a 15w 40 that isn't a diesel? And if they did why would an oil change place stock it? It would have to be pretty rare. I got no problem with blends. I was using a store brand 5w-40 blend for several years in almost my whole fleet except the new VWTDI that is still under warranty and dealer care. Used it 3 of my burbs, all over 200k on them. Both my 5.7 cars as well as a 57 pontiac and a 70 442 and a 73 Caddy. Also use it in al the small engines like mowers and such. 2 or 3 years ago they quit selling it but have a full synthetic in 5 gallon pails so I switched to that including in the current burb which has a crap ton of miles on it and its still happy as well as everything else.

I think most of the synthetic oil issues and stories come from its early days which was the 1970's. Back then it was a different and apparently incompatible animal. Now days it hardly even cost more than regular which can be harder to find in some areas which usually means less compition so higher prices if someone does stock it.

Well put.
There are a lot of 15w-40 diesel full synthetic oil now also.
Mobil comes out with Diesel Extreme.
The Delvac Super 1300 is not syn blend 15w-40.

At any rate, most of the synthetic is Group III which is just a more refined dino oil.
Group IV is the real synthetic but in this case, it is NOT 100% either, it is usually mixed with Group III.
There are a lot of research with oil that prolong an engine life without overhaul.

 

[JMJNet]

@JMJNet Was there an unintentional mistake in your post? Mobil says Super 1300 is a synthetic blend. Just used it. Mobil Delvac™ 1300 Super 15W-40 diesel oil | Mobil Delvac™ Engine Oils

It should say "Now", the spell checker.