The reason why the 5w-40 makes the truck start smoother is that the 5w oil is thinner than the 15w when cold, and once it is initially pressurized by the HPOP, it flows easier to the cylinder heads, and it is pushed into the injector easier. With the 15w, it has somewhat of a lag, and the injectors are compromised for normal PSI, and it fluctuates down and up, causing the romp noise on startup. The synthetic costs about twice the price, $15 a gallon instead of $7, however i think the stuff is alot better. It's in a dark blue bottle, walmart.

 

Just switched to 5W40 yesterday. Where it had been taking 30+ cranks to get started, today it took 8 or so. I'd say that's a pretty good improvement.

 

Strokin_it7.3.......do they have Shell Rotella 5W40 in dino?.....I just did my oil change not too long ago, and if I can, I'd like to avoid paying $15.00/gallon for oil right not......Later on is a different matter. I will if I have too, though.......

 

The 10-30 Rotella has the HD diesel rating that the 15-40 has. However, it is for temperatures under 80 degrees - no problem where I live, but even I don't run it in the summer here in Wasilla. I run the 15-40 Rotella then. Like the others have said above, the lighter weight oil will make it start like it is summer outside. It is hard form me to believe that it makes as much difference as it does, but it really makes THAT much of difference.

 

I'm not sure that they market the light dino oil in your climate zone. They may though if you look high and low.

 

Alright.....I'll just look.....

At my folks for dinner......My Dad's a Duramaxer (2004)......Told him my problem...said that his truck is set to run 5W40 year-round (gets his serviced at Chevrolet), then of course threw in the jibe "Of course, you couldn't expect something simple like that to apply to a chincey Ford"!.....

Lots of Ford/Chevy battles in my family.....(haha).

Steve

 

Actually, your problem is called 'ROMP, ROMP, ROMP' - and very common with cold weather starts.

Not to take anything away from the previous posters here, but it's an easy fix (90% of the time), and won't cost you a dime, only about 20 seconds more of your life each morning.

Here's a thread I started a while back on the same issue. Post #12 is your fix, and did work for me.
Another Cold Start Surging Idle

 

Interesting....I always wait for my fuel pump to cycle before I try to start it up. Usually, it turns off all by itself well before the glow plug light goes off. In fact, I used to cycle to the key a few time in extremely cold weather (colder than -5 degrees F) hoping that the glow plug temperature would help it start. It never has made any difference for my truck. It just must be too cold out for it to make any difference in curing the romp, romp, romp problem. From my experience while living in a truely cold climate (a few places in the lower 48 get this cold - just not for the duration of time) in Wasilla, AK is that there are only two ways to "cure" the romp, romp, romp, romp problem. In fact, sometimes it is so cold here (-30 F to -40) that you are glad just to get the romp, romp, romp and get your truck running. The only sure way to get rid of the romp is to plug your truck in or park it in the heated garage. The other way that will really really help but not cure this "problem" is to change the oil to 10-30, or the 5-30 synthetic and even with this oil it will still do it if it gets cold enough. From my experience it seems to start doing this again in my truck at about -10 to -20 without the truck being plugged in on a cold start. However, it will still start - something that would be more miss than hit with 15-40 when it is that cold. Something that you are very thankful for when you are away from a plug in and away from town.

 

Post #12...Interesting.......Alright, I usually let it ride a few seconds after the glow plug light indicator shuts off, but I'll let it go a while longer and see if that does it. Thanks.