has anyone mixed or switched from synthetic to conventional oil on accident or not and had instant sludge causing a no start condition? I did I was just curious if I was the alone or not

 

You can switch freely between both with no issues.

 

What two oils? Can you post a picture of this sludge?

Can you send a sample of the sludge off to get analyzed?

 

You can mix oils till your hearts content... they make synthetic blends, although I always use straight synthetic. No issues running one or the other or mixing them. So curious how/why you have sludge.

 

Perhaps there was sludge already in the engine and the synthetic oil loosened it up and caused problems but still very unlikely

 

That is certainly not an oil problem. When I drove(and maintained) over the road semi trucks that ran into northern Canada we would run synthetic 5w-40 in the winter and conventional 15w-40 in the summer in the trucks. Several trucks with different engines with no problems. Did it for years.

 

Howdy,

I have also switched from Non-syn to Syn seasonally as mentioned above with no ill effects.

In diesel engines, sludge comes from build up of combustion (and other foreign) products that are not kept in suspension and/or trapped by the oil filter.
This process continues until the dispersants (AKA detergents) can no longer keep those combustion products (soot and other "stuff) in suspension.

You have to NOT change the oil for many hours(miles) past the recommended interval for those products to begin to "drop" out of suspension.

Commercial operators use UOA (used Oil Analysis) to determine when they are getting close to this point. All the rest of us when running modern synthetics can likely go up to 50% or more past the recommended interval before even coming close to this point.....(Although I wouldn't and I don't know anyone who would!)

"Sludge production" was really more prevalent in the days of oils meeting API SA designation ("NON-detergent"), vehicles with no oil filtration or people NOT changing oil at all!

Since with API SA there was no additives in the oil at all, (no "detergent"), pretty much all the combustion products that were heavier than the oil would settle anywhere that was horizontal and didn't have sufficient liquid flow to keep them moving.

Today, unless you're using "Straight Mineral", API SA or Non-detergent oil , etc, and you use and change recommended type oil at the recommended intervals, It's very unlikely you'll ever have an oil related problem.

There are no modern motor oils that will produce "Instant Sludge" simply by mixing them together.

If you want to read more about oils, here's one of my favorite information sites. https://www.machinerylubrication.com/

Cheers,


Rick

 

It appears that the originator has lost interest in any feedback ...............

 

He didn't like being called out on lack of maintenance being the cause.

 

I’m sorry I didn’t get back to you guys I really appreciate the input I am sending it off to be tested and I replaced the oil cooler a few months ago and use rotella t6 and it is clean as a pin inside I got some conventional oil out of a drum at work and it says 15-40 on it and that’s about it so I’m considering the label at this point

 

Well? Any thoughts on flushing oil cooler?
Preventative maintenance. 😃 Sludge and those super small fins in an oil cooler doesn't sound good.
I would if it was mine.

 

Form your post above, I would advise to take more care in what oil was added to the engine.

You make it sound like it was a bulk oil that had been sitting around a long time (since you suspect the label didn't represent what was in it) ..... so, maybe it contained something else, maybe it wasn't diesel oil, or maybe even it was waste oil and had water in it. I mean, who knows what you put in your engine.