I have heard all kinds of different things - so I figured I'd just ask. I put Rot. Syn. 5w-40 in my truck for the winter, but I will need an oil change in the next couple of weeks. I have always run Rotella dino 15w-40 in my truck year round before this winter - I switched to see if it would make it start a little easier in the cold (I basically have NOwhere to plug my truck in) - and it DID! But I swear it runs a little smoother all the time - even when up to operating temp. The price doesn't bother me at all - so my main question is - is the 5w-40 weight synthetic OK to use year round - or should I switch back to 15w-40??? I live in PA - so high temps we see are mainly 90*s - hardly ever over that. Any thoughts would be great. Thanks!

 

i asked that same question a while back, and i kinda forgot, but i think they said it was alright, or did i ask if i could switch back to 15w40 after using the 5w40 synthetic? ahhh i forgot now, but somebody should give an answer soon

 

Cat, I use it year round. Have already gone thru two summers. No problem. Carroll

 

cat, i run that weight oil all year and its fine. the rating on oil goes as such; the first number is the viscosity when cold, so 5-40 is thinner then 15-40 when cold, and only when cold. the second number is the viscosity at operating temp, so a 5-40 or a 15-40 will hold the same viscosity at operating temp

 

I have a '99 f 250 psd, and was wondering the same thing, I posted a thread on the Shell Rotella forum asking about using the synthetic year round. The Tech told me that it was a good year round oil, so I will be using the Synthetic from now on.

 

It is rated as 5 weight @ 0 degrees and 40 weight @212 degrees. 15W- 40 is rated at 15 weight @ 0 degrees and 40 weight at 212 degrees.
They have the same viscosity grades at warm weather operating temperatures, so it is fine to use either.
The synthetic is better for cold weather than dino because it has much lower viscosity at cold temperatures, increasing flow rate and decreasing the effort required by the starter to spin the engine.

 

Rotella 5W-40 synthetic all year.

 

Alright - thanks - guess I might just stick with Rotella Syn. from now on. I usually changed my dino 15w-40 every 3-4000 miles, but am planning to go the full 5000 with syn., so that should help off-set the cost a little bit. I never get good milage in the winter, but am interested to see what happens with this oil in the summer.

 

i was at wally world the other day, it was somewhere around 6 bucks for a gal of either chevron delo, or the shell rotella 15w40, but when i looked at the shell rotella T 5w40 synthetic, it was 12 something! holy macrel, 6 bucks more for synthetic and 5w40

 

That's actually not bad at all really - I take it you've never seen the prices of some of the other Synthetics that are out there!!!

 

I second that Cat_Man, I liked to have passed out when the guys at the Ford house I go to let me work on my truck on a weekend there a while back. They wound up giving me the syn. gear lube I put in both my axles when I changed that, but they told me that stuff is 20 something a quart for that stuff... I would sure hate to think I would have to pay that kind of money for the oil to go in the PSD...