Is their a serious downside to using 10W40 as opposed to 10W30 in a
2002 TJ as I appear to have a lot more choice of oils at this weight than the 10W30 in full synthetics. I was reluctant to go down to the 0W30 & 5W30 unless anyone has an opinion to the contrary as I do not need that amount of cold weather starting capability.Cheers Nick
The first number doesn't matter that much, but the second does. I've been running 5W30 for quite a while and it works fine. Now if your in a very hot climate then 40W will work well. When all else fails consult the service manual or call a local Jeep dealer.
What does your owners manual say there are reasons for that and to numerous to mention just follow your manual you can never go wrong. Coasty
I run 10w30 90% of the time in my TJ. But when I make trips out to the colorado river where the temps hit 120+ on he AZ/CA border I use
10w40. I have heard some horror stories in other groups regarding 10w40 with too many polmers being added which makes the oil break down quicker. I don't buy into it. Just change your oil at regular intervals and you should be fine even if you do run 10w40.In fact I have an over worked 150k miles dodge neon that I beat up on a 90 mile commute every day, and run 10w40 on the smoking hot days of socal desert summer. Never had any issues with this engine. Maybe I'm just lucky.
The stories are correct. This problem can be really bad with conventional 10w40 in a engine especailly if you do not change it very often. (GM had some much truouble with the VI in 10w40 cooking out in piston rings in 80's and cause them to stick you will not longer find
10w40 as a approved oil for them since that time. use 10w30 or 15w40 but stay away from 10w40 conventional oil.----------------- TheSnoMan.com
I am currently using Redline 10W30 which costs me about £50 every six months so I was looking for a cheaper alternative as I only do about
1500 - 2000 miles every 6 months. Unfortunately Redline appears to be the only 10W30 I can find in the UK as a full synthetic. Looking at the Jeep Workshop manual 10W30 is the prefered and from the chart 5W30 has a lot lower top end temperature than 10W30 which is why I was concerned whether to use it, I can find loads of 5W30 fully synthetics but was just considering the 10W40 as it had a hotter top end.Cheers Nick
5W30 is 30 at operating temperature and flows easly at freezing and below. It is compatible with modern vehicles.
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