10W40 on a 3.4L

[MustangEater8251]

its reccomended 5w30, but the norm fpor most flroida driving is 10w30(used at dealerships)

Any potential problems running 10w40?

I am thinking there will not be any real effects, I am jsut trying out that valvoline max life stuff to see how it works out. And it came in 10w40

[Brian Dieckman]

5w30? Realy? I didn't know that.

I've been using 10w30 Valvoline Max life through three oil changes now, and I've had no problems.

I dont know what the PO used, but it has 80K on it, and I thought it was time for some more application specific additives.

I say go for it. Its obviously not under warranty, so you're taking your chances, but hey... What's to lose?

The worst I can think of is that the oil pump will have to work harder at first, but that shouldn't be a problem.

-Brian

[pvtschultz]

Don't worry abou thet 10W40 oil. It is a little heavier, but is supposed to still flow like 10w30. That is what the 10w part is for, but remains more viscious when hot. I use 10w40 in MN/WI during the summers, no probs.

[MustangEater8251]

I was thinking being a little thicker may be beneficial(low oil pressure), unless it is my oil pump that is causing problems or if my oil screen is clogged.

Ehh... only one way to find out [img]smile.gif[/img]

[94CaliCamaro]

They make Max Life 5W-30, would it be better to use the 10W-30?

[mwh27]

The hayne's manual for 3.4 reccomends 30W for temps above 40F....

So I think im gonna run a solid weight this summer.

Thoughts? Concerns?

[FunkZ]

I normally run 5W30 year-round in PA. I used to run 10W30 in the summer, thinking it would be better to use when it's hot because the 5W30 stuff gets so thin it's almost like water. But I noticed I get worse gas mileage on 10W30 than I did on 5W30 so now I just use the 5 all the time.

Figured I'd add I'm at 160k miles and it doesn't use any oil either, despite the myth concerning switching to synthetic on a high-mileage motor. Over the last 8 years I went from conventional to semi- and now to the full synthetic Mobil 1 Extended Performance 5W30. About 7k miles so far on this last oil change and so far so good. Oil color and consistency looks good and level is spot on. I'm going to hit the 12 month oil change interval before I put 15k miles on it though.

[ November 01, 2005, 02:34 PM: Message edited by: FunkZ ]

[camaroman1181]

i wouldnt use a straight weight.. i always use 5w-30.. no problems and i dont use a drop of oil at 140k miles... and yes, you will notice a decrease in gas mileage using 10w-30 since the viscosity is greater and it adds more resistance to the motion of your engine parts.

[shenanigans]

Originally posted by mwh27:
The hayne's manual for 3.4 reccomends 30W for temps above 40F....

So I think im gonna run a solid weight this summer.

Thoughts? Concerns?

holy **** dude... I sold my 3.4L 2 years ago and you brought this post up [img]graemlins/rofl.gif[/img]


I had no problems running 10w40 on my 3.4L... no changes in anything...


and reason in the end why my oil pressue was low was a bad oil pressure sending unit.

[FunkZ]

LOL, whoops missed that date thing...

[mwh27]

I should be praised for using the search [img]graemlins/banana.gif[/img]

[ezrollin]

hmm mix mostly 5w-30 with a little 10w-30.
i usually run 10w-30, the manual says so.
i'll eventually switch to synthetic.
an autozone guy told me it'd be bad to mix synthetic and conventional(non-syn)

[mwh27]

Originally posted by ezrollin:
hmm mix mostly 5w-30 with a little 10w-30.
i usually run 10w-30, the manual says so.
i'll eventually switch to synthetic.
an autozone guy told me it'd be bad to mix synthetic and conventional(non-syn)

Uhhhhh, isn't 5W-30 printed on the cap.....

[Publican]

The Owner's Manual in my '95 3.4 is very specific - 5W-30 is the oil. If warm temperatures, 10W-30 MAY be used. It states in capital letters I believe DO NOT USE 10W-40 OR 15W-50 OR OTHER MULTI WEIGHTS. I think it also says if no 5W-30 or 10W-30 available, you can use straight 30 weight as a temporary substitute.

The manual is not quite so stringent on a 3.8 - I think 10W30 is the recommended oil.

GM brought out a series of engines in the 90's that specifically called for 5W30 - don't know why or anything about the engineering.

I use Mobil 1 or Pennzoil Full Synthetic 5-30 - 102K miles & just like new!

[camaroman1181]

the autozone guy is a moron.. what does he think synthetic blend oils are. Ive run them for 4 yrs now and have had no problems. and yes, the manual and the cap both specify 5w-30. The manual says you can run 10w-30 under certain conditions. I've ran 10w-30 once or twice but noticed a power loss (as to be expected with the thicker viscosity). Thicker oil does seem to protect better as long as oil passageways and such are designed to flow the more viscous oil at adequate flow rates. Personally, I dont think it would make a real big difference either way except youll see less power and less mpg with the thicker stuff.