Cold starts=Hard Starts

[Cherokeekid88]

Well heres the deal, on days its like about 45 or so, the jeep starts fine. but on days like today where its in the 20's lower 30's the jeep will start rough and then smooth out. When i get it, i always let the fuel pump run for about 10 seconds or so, then i go to start it, it always fires up on the first crank but it sounds wierd for like the first 1.5 seconds and then it will smooth out and run like a champ. Wondering if its something wrong or if its because im running a thicker oil - 10w40 or what?

[UNCC_99XJ]

Mine's been doing it ever since I got it. 3 years now and no problems.....just the nature of the beast I guess?

I usually let it run a few minutes regardless of outside temp on a "cold start", just to give things a chance to start flowing.

The true test will be, does it start tomorrow morning at 13 degrees outside...

[Cherokeekid88]

HAHA yeah tell me about it! it just feels like im gonna throw the belt right off the pully!

[BLKXJ33]

Would'nt worry bout it... thats just how a 4.0 acts in cold weather, the oil shouldn't have anything to do with it... how many miles are on the ticker?

[jimmydaux]

Technically youd be better off getting a thinner oil in there during the winter. Its easier to pump it when its cold and should help some on the colder days.

[Cherokeekid88]

well i though you are suppose to run a thicker oil in the winter to keep from freezing, and a thinner wait in the summer. 173k on the ticker

[UNCC_99XJ]

As mentioned, thinner oil in colder weather.....easier to pump and get moving. Also a thicker oil in the summer, as you dont want it to get too thin.

With that said, I've always run Mobil 1 10w-30 year round with no problems, since we dont normally have the extreme cold temps like we are right now. Considered dropping it to 5W-30 in the winter, but i'd rather not speed up my rear main leak any more.

[BLKXJ33]

Thinner in winter...easier to pump through motor on cold starts. Summer dosent really make as big of a difference. I just stick with 10w30 unless the motor leaks or is noisy, then I might step up to 10w40 or add a quart of lucas goo.

[BLKXJ33]

Originally Posted by Cherokeekid88

thicker oil in the winter to keep from freezing

What are you refferring to freezing... no fluids should be freezing unless its your wiper fluid