Engine Oil Recommendation | Occasional Start up Issue

RCOAKLEY

MEMBER
2005 JEEP GRAND CHEROKEE
3.7L
6 CYL
2WD
AUTOMATIC
138,250 MILES

I'm more so interested in a recommended oil to use with my vehicle at this age/milage.

Other questions include:
1. Why do I occasionally have a problem starting my Jeep? The first start would fail, the second crank always works. This happens with every other start (not every start).

2. I have been topping off my oil with 15w40; one bottle every few weeks. It seems I have a leak of some sort by there are no visible signs anywhere of a leak (i.E. Oil stains under the vehicle).

3. What type of treatment is recommended for my engine? I will be performing service in a few weeks and I want to do as much as possible to get a nice flush.

4. When idle, my RPMs occasionaly dip and there is a heavy vibration as a result of this. The engine recovers and everything always goes back to normal in a matter of seconds. This happens every so often (probably once every other week at it's most frequent).

3 Replies

HMAC300

MECHANIC
48,601 POSTS

As far as oil use 5w30 or 10 w30 that is what manufacturers require. 15w40 is to heavy and makes the ring screw up because they are light tension. Try cleaning throttle plate on both sides and iac hole with choke cleaner see if you idle problems clear up. If not check fuel pressure with a gauge. As far as flushing I imagine you are talking about coolant, so drain what is there all of it if you can an dreplace with 50/50 solution Chrysler recommends Hybrid Organic Additive TEchonology or HOAT or it's equivalent.