Hey guys i have a 90 jeep cherokee 4.0 with 208,000 on the clock. when i bought it i changed the oil with rotella 15-40 and a wix. A lil thick for winter but really don't reach much lower then 20 degrees, which i believe 15-40 is good till 10 degrees. i drive it fairly easy in town but when i'm offroading or around mud i'm pretty hard on it(reason for buying it in the first part). It uses oil, a lot more when 4k rpm or more and the vacuum harness gunked up but anyway i'm happy with the oil, from what i've seen since buying it its done a good job cleaning it so far. I'm considering trying out the syn T6 5-40 next change, should I? Or should i try a new one or stay with the 15-40, keep in mind it does get beat up. thanks
what do you guys think?
- Thread starter xjwheeler32
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No, i wouldnt. It will likely burn more with syn and end up costing you more for top-offs. Can you switch to a high mileage oil?
10w-40 Valvoline MaxLife or Pennzoil High Mileage
If you really wana try the syn, go for it. 5w-40 T6 is a great oil, it will definitely burn on the first oil change with the T6, so wait till after your 2nd oil change to determine if its worth it. In regards to burning, clean/replace your PCV valve if you have yet.
10w-40 Valvoline MaxLife or Pennzoil High Mileage
If you really wana try the syn, go for it. 5w-40 T6 is a great oil, it will definitely burn on the first oil change with the T6, so wait till after your 2nd oil change to determine if its worth it. In regards to burning, clean/replace your PCV valve if you have yet.
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i can try a high mialage, i was too looking at pen defy, any feedback on that? the reason to look at the 15-40 convetional oil or the T6 syn is they are only 12 bucks a gallon at my wal-mart.
Does the owners manual really spec a 15W40? I thought it said just 5W30 and 5W40.
How do you know its done a good job cleaning? Have you done a before/after inspection of the valve area?
How do you know its done a good job cleaning? Have you done a before/after inspection of the valve area?
yes have looked under vavle cover before and after, and was suggested by other jeepers that the rotella 15-40 was a good oil for these flat tappet cam motors. i also used it to help with consumption, manual recommended probably wouldn't help, i'm not against it but in my case i feel there are better oils then recomended.
Sounds like your 4.0 is getting tired, most of them don't use any perceptible amount of oil at all. Rotella is good stuff for sure, normally I'd say 15w40 is gross overkill but for your high miler it might be an okay choice.
How about a 10w40? You can maintain the thickness you are liking but get a higher VI, better flow and cold start performance than the near molasses 15w40.
Maxlife 10w40 could help with consumption too...and Castrol GTX High Mileage 10w40 is probably just as thick as your 15w40 but would have a much higher VI as well.
How about a 10w40? You can maintain the thickness you are liking but get a higher VI, better flow and cold start performance than the near molasses 15w40.
Maxlife 10w40 could help with consumption too...and Castrol GTX High Mileage 10w40 is probably just as thick as your 15w40 but would have a much higher VI as well.
Thanks kcjeep I think I'll try a hm oil next, 10-40 is prolly the best for my case. I'm sure its getting tired but still has great power
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