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?
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Is Mystik JT8 15w50 a good oil for a semi truck?
- Thread starter Redland1
- Start date
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.
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.
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.
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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.
‘03 that isn’t emission controlled, other than possibly EGR(?) CI-4+ is plenty good enough, and Mystik makes some good HDEO.
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I say mine was stolen...
Of course it's good, has all the certifications and is used often in the agriculture industry among others.
Mystik is a Chevron brand
Mystik is a Chevron brand
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
Which, of course, you meant citgo.
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.
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)
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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.
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.
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.
Beautiful truck