different oil viscosities??

[IrishChamp]

for my first oil change I switched from the oem 0w40 to 15w50 which I've used for the last two changes. I got my hands on some 5w40mobil diesel truck blend. I've heard that this oil is perfect for our cars but I'm no expert and would love for some people with more knowledge chime in. Also, is it bad to change viscosities too often or too many times? I'd like to use this oil because its sitting in my garage but I may have to change oils again after my turbo build if jeremy suggests anything special.

[stevesrt8]

the only way you would even remotely hurt anything would be if you used something too thick at start up and you live in Antartica. Or if you used something too thin and ran it hard across Death Valley.

I have experimented with 15w-50 in my car and it made absolutely no difference in the infamous whine. So I run Amsoil 20w-50 racing oil and it's quiet as a mouse. Since my car is stored in heated garage cold starts are rarely an issue, and the car seems to love it.

[ekaz]

I'm debating this as well since I did the heads/cam switch. 20-50 is too thick for the spring/fall/winter in Chicago. I was thinking the 15-50 or 5-something at the next oil change as well.

[MrC1]

The oil weight with the 6.1L isn't quite so sensitive as it is with the 5.7 since we don't have MDS. Just use common sense based on climate and I'm sure you'll be fine.

[done]

for my first oil change I switched from the oem 0w40 to 15w50 which I've used for the last two changes. I got my hands on some 5w40mobil diesel truck blend. I've heard that this oil is perfect for our cars but I'm no expert and would love for some people with more knowledge chime in. Also, is it bad to change viscosities too often or too many times? I'd like to use this oil because its sitting in my garage but I may have to change oils again after my turbo build if jeremy suggests anything special.

Why not just use what the manufacturer reccomends? They built it and they warrant it. Perhaps they know something?

[Doctor No]

Stick with 0W(winter)-40 Mobil-1 at least for fall winter spring.I would only use 15-50 for summer months due to 15-50 being to thick for cold start and first few minutes of operation to give proper protection.

[slideway]

I'm using syntec 0-30w this winter, It was on sale for like 4$ a quart. My oil temp. never even sees 200* in winter. Between 180-190* most of the time.

[NOTPAID4]

I bought 5w30 for my last car... still have a lot of it left. Is this too thin for the 6.1?
It doesn't get that cold here, usually, at night, around freezing. It's MOBIL 1 5W30, EDTENDED RANGE. Hate to just having it sitting around. Wally world locally sells there 0w40 for 5.96 per qt. (cheapest I could find). Another post only got one reply and he said his friend used this oil but his 300c, 6.1 smoked using this. thanks, Jim

[slideway]

I would use it, but thats just me. you could also blend it with the 0-40.

[MrC1]

Use it, 5 is reat for pretty low temps and 30 is plenty for 90% of the hot stuff. You're good.

[done]

Why not just use what the manufacturer reccomends? They built it and they warrant it. Perhaps they know something?

Oh well, guess you just can't be a "Car Guy" if you follow the manufacturers reccomendations.

[IrishChamp]

I don't think they will warrant it after the forged 392 short block and the turbo is strapped up.

Why not just use what the manufacturer reccomends? They built it and they warrant it. Perhaps they know something?

[NOTPAID4]

Thanks for the info guys... even though mine is an 06 Mag SRT8, it only has 2700 miles... getting ready for it's first change !!! I do have some 10w40 mobil 1 also and you say it's OK to mix different viscosities... ? Jim