Is Mystik JT8 15w50 a good oil for a semi truck?

[Redland1]

Hi.Looking to switch to the Mystik 15w50 because my 03’ Cummins ISX15 is getting up there in miles and I want a heavier oil to keep the oil pressure up and consumption down as it wears.Is that oil a good choice?

 

[ripcord]

Is the oil pressure low? Cummins want's to see 15psi or higher at hot idle and 35 to 40 psi when rev'ed up.

https://mart.cummins.com/imagelibrary/data/assetfiles/0059588.pdf

That Mystik oil is only CI Plus rated which is an older spec. I would choose a CJ or CK oil for your emissions controlled rig.

 

[Redland1]

Is the oil pressure low? Cummins want's to see 15psi or higher at hot idle and 35 to 40 psi when rev'ed up.

https://mart.cummins.com/imagelibrary/data/assetfiles/0059588.pdf

That Mystik oil is only CI Plus rated which is an older spec. I would choose a CJ or CK oil for your emissions controlled rig.

Lowest I’ve seen is 16 but almost always 19-20psi at idle.Emissions fell off on a real bumpy dirt road.Truck is an 03’.

 

[facility1]

mystik is made by citgo,, long time ago i used the 10w-30 and the 5w-30 mystik dimension semi-synthetic,,,was a decent oil

 

[Chris142]

Lowest I’ve seen is 16 but almost always 19-20psi at idle.Emissions fell off on a real bumpy dirt road.Truck is an 03’.

Sounds ok to me.

 

[bullwinkle]

Is the oil pressure low? Cummins want's to see 15psi or higher at hot idle and 35 to 40 psi when rev'ed up.

https://mart.cummins.com/imagelibrary/data/assetfiles/0059588.pdf

That Mystik oil is only CI Plus rated which is an older spec. I would choose a CJ or CK oil for your emissions controlled rig.

‘03 that isn’t emission controlled, other than possibly EGR(?) CI-4+ is plenty good enough, and Mystik makes some good HDEO.

 

[JavierH19]

I'd use it, better than 15w-40 and lucas which some truckers use when psi's low.

 

[oil pan 4]

Lowest I’ve seen is 16 but almost always 19-20psi at idle.Emissions fell off on a real bumpy dirt road.Truck is an 03’.

I say mine was stolen...

 

[alarmguy]

Of course it's good, has all the certifications and is used often in the agriculture industry among others.
Mystik is a Chevron brand

 

[fantastic]

In this situation I'd run it. Should be good oil.

 

[benjy]

a decent oil for a good price, many motor cycle owners like. in my lo mile 50+ thou loose audi TT tuned 1.8T i see higher vacuum + less consumption with Redlines 15-50 real synthetic, but only 4.25 qts so cost is not bad!!

 

[tnt_motorsports]

Hi.Looking to switch to the Mystik 15w50 because my 03’ Cummins ISX15 is getting up there in miles and I want a heavier oil to keep the oil pressure up and consumption down as it wears.Is that oil a good choice?

currently running the 15w40 JT8 in my 2012 Ram Cummins. First fill and no signs of issues. It will be a while before I UOA with winter upon us, but my first impression is this is a good oil and is reasonably priced IMO.

Just my $0.02

 

[simple_gifts]

Of course it's good, has all the certifications and is used often in the agriculture industry among others.
Mystik is a Chevron brand

Which, of course, you meant citgo.

 

[bullwinkle]

a decent oil for a good price, many motor cycle owners like. in my lo mile 50+ thou loose audi TT tuned 1.8T i see higher vacuum + less consumption with Redlines 15-50 real synthetic, but only 4.25 qts so cost is not bad!!

Not sure where the OP is buying it, but I bet a 5 gallon pail of JT-8 isn’t a lot more than 5 quarts of Red Line!

 

[Redland1]

Not sure where the OP is buying it, but I bet a 5 gallon pail of JT-8 isn’t a lot more than 5 quarts of Red Line!

$90 a pail.

 

[alarmguy]

Which, of course, you meant citgo.

ugh ... yes ...

I have used JT-8 extensively in my 2014 Road King for 8ish years. Many UOAs in here, oil temps in the bike would run as high as upper 660s stuck in traffic a few times. Last oil change, for fun switched to Mobil 1 15/50
It's a rumor I could never confirm that Harley oil is produced by City. True or not I don't know but the only place I could ever buy a HEDO 15/50 which the HD oil is said to be formulated like, no documentation, except HD call for diesel oil if their 20/50 oil is not available. With the disclaimer to change back once it is (of course ha ha)

 

[Foxtrot08]

The Mystik 15w50 is designed for older agricultural equipment. By older, I mean pre-Tier equipment, so from the 1940’s to the 1990’s.

Will it work in a 2003 ISX? Yes. Would I personally recommend it? Not really. If you’re losing a lot of oil pressure, you’re going to have something mechanical going on. I would start with that instead of throwing a (fairly) expensive oil at the problem.

But to answer the question, it’s a good oil. Certainly has a niche in the market place.

My fleet still has a few 1980’s to 2007 engines out there. (Mostly CATs) and we run all 15w40’s in them.

 

[Chief119]

I run it in my 2019 Pete, I have 160k on it so far and it’s been doing great! This is a Glider Kit with a C15.

 

[bullwinkle]

$90 a pail.

I wasn’t too far off-
https://www.redlineoil.com/15w40-diesel-motor-oi

 

[Redland1]

I run it in my 2019 Pete, I have 160k on it so far and it’s been doing great! This is a Glider Kit with a C15. View attachment 193875

Beautiful truck