'Synthetic Blend' is normally used on labels to describe a semi-synthetic oil.
If that is the type of oil used i.e. a semi synthetic 15w40 diesel oil, you should have no immediate concerns.
If you doubt they used a diesel oil, change it out for a diesel oil, sooner rather than later.

If they did actually use a 15w40 synthetic, the same considerations would apply, except that, a diesel synthetic is likely to be as good or better, so long as the oil manufacturer states it meets the oil performance grade suitable for your engine.

Short story is, don't trust the service centre to use the correct or most suitable oil.....DIY !

cheers

 

I been doing my own oil service on my trucks for years with Rotella T4 15/40. The oil they used was Castrol 15/40 which was a surprise to me as I didn't know Castrol even made a diesel grade oil. I'm just not a firm believer in synthetic oil in diesel engines. Thanks for the input 👍.

 

You shouldn't have any issues

 

As long as they used a Diesel engine rated oil you will be fine. I used Syn blend Rotella T5 all the time in my engine. I switched to full syn T6 5-40 many years ago because my engine just likes it better, runs smoother, and starts far easier in the Brrr cold -freezing weather.

 

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.

 

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.

 

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 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.

 

Yeah The new "Triple protection" Rotella T4 is a blend too. Most all multi grade oils, anymore are a blend of all kinds of chemicals. Both petroleum based and synthetic.

 

Synthetic blend 15W40 is okay to use.Years ago I used Quaker state 4x4 semi synthetic 15W40 blend oil in my 5.7 diesel.It used to be in a clear bottle but it was decent oil.Napa in my area used to sell it.I’ve since used Mobil delvac sae 30 weight in both my Chevy trucks

 

I just picked up another bucket of a store brand 5w-40 and it was $69. That's $3.45 per quart. I just looked up Rotella T6 at wally world and thats $22.68 so $5.67. Seems like my last bucket was in the low $50's and last time I bought the T6 it was like $17. Guess the days of $1 per quart are long gone. Even 5 years ago I was picking up Napa brand synthetic for like $2 per quart when they had their sales.