was in the tractor supply store today to purchase motor oil for my 99 cummins and came across some oil called mystic 15-40w synthetic and i think it said jp-8 or cl-8 .Has anyone used it or heard of it also since i have owned the truck have never used synthetic,can you just switch over to synthetic. i normally run rotella or delo 15-40 with a little lucas oil stabilizer,have about 180,000 miles now ,also just started running 2stroke oil in the fuel,had some husqvarna xp premium hope that was ok,what brands do you all prefer. New to this section ,think it is awesome.thanks for your input.

 

Not all that familiar with mystic and what base stocks they use. It was a synthetic? I'm going to put a combo of your letters together and make a bet that it said CJ-4?? This is just the API rating on most of today's oil. There are still some olders around but these are required in the 07 and newer engines. Will still work fine in yours.
You can switch over to syn, they mix fine. Couple of things to consider:
With high miles, there's a chance that there may be some sludge and varnish build up going on. Syns can start to clean that up. If there is a plug holding a leak in a gasket by chance, it may come unplugged. Also, if it is cleaning things up, you will need to change the filter sooner than normal. If you notice it starts burning it quicker, you can try changing filters and see if it improves. I have seen where older trucks start burning the synthetic and the filter doesn't help. Sometimes the rings are old and little compromised. Good enought yet to hold back a dino but syn seems to split by.
All possiliities, but non may happen. I had a 94 with 269,000. It used/leaked one qt every 3000 when I got it. I switched to amsoil anyway I fixed the leak but it took about 10-15k, but my usage slowed up. It was only using a qt every 4-5k. I was ok with that.
Another option is to flush an engine and get any garbage out that may be in there. Some do and some don't.
All things to consider with your truck. Many advantages to synthetic too.
If you're looking at synthetics, I might suggest amsoil of course, but mobil would be my next choice.
Good luck.
PS...if you go synthetic, recommend not using the lucas. Additives aren't recommended by oil manuf...unless they are making it. Can affect the chemistry of the oil.

 

Thanks for your reply, will take all into consideration and of course i have half a gallon of the lucas oil stabilizer left ,once it is gone will switch over to synthetic, also can i do the engine flush myself. Thanks again

 

The flush is simple. We have one but I'm sure there are others out there, I've just never looked. Here's a look at our's:
flush

IF you do it, get yourself a cheap oil filter. You will need 2 bottles of flush. Take your filter off and replace with new (cheap)one. Dump the 2 bottles in the sump and run at high idle for 20 minutes. Drain oil and change filter to your regular filter. That's it.

 

I run the Mystik JP8 in my duramax. It is a semi-synthetic 15w-40. I like it. Usually around $12 / gal. at TSC. I wish it came in a 2.5 gal jug instead of a 2 gal jug.