OK, i know there are numerous threads about motor oil (and I have read most of them), but I have specific questions about the Mobil 1 5w-30 and 10w-30.

The manual of my 02 P5 calls for 5w-30 for up to 120°F (correct me if I am wrong) and 10w-30 for anything above. And every single article I can find on the web says follow the manufacturer's recomendation.

However, my logic goes like this: Mobil 1 5w-30 should out perform conventional 10w-30 even at high temp. So if conventional 10w-30 is good for all temp in a stock P5 engine, mobil 1 5w-30 should be more than enough, right?

I was looking at 5w-30 and 10w-30's specs on Mobil 1's web site and they are very close and have the same flash point (455°F). I know one of the reasons for choosing the smallest spread of engine oil viscosity is because the less viscosity improvers in the oil, the better. However, I think (if my memory serves me right) neither of them need viscosity improver to achieve their rating.

It seems the only difference between them is the better pumpability with the 5w-30 at low temp. Now, am I too far off to assume that they protect engine equally well at the same operating temparature (well, say in a 2002 P5 stock engine)?

I live in the bay area and temp ranges from the 30's in a cold winter night to the 90's in the summer (100+ for couple days a year). I think it is well within the operating range for both grades. I am planing to use 5w-30 all year long for it's better startup protection (most engine wear and tear happens at startup, right?) and possibly a little better mpg. So, do you think 5w-30 can handle the hot days in summer (could be 120°F+ on the tarmac) and ocassional trips to Vegas?

What do you guys think...? Am I just thinking too much and should spend my time to think about something more important (like which cat back to get )?

 

i live in tx and i ran 5w10 mobil 1 synthedic. it really doesn't matter just as long as u run one or the other. the 5w30 is better during the cold season, the engine turns over easier when cold starting, but thats a given

 

Check your manual...I think it said to use 5w up to about 95* F or so, can't remember for sure...So I would use 10w-30 in the dead heat of summer, and 5w the rest of the year...

 

the manual says 105 for 5w and well over 120 for 12W

 

ok thanks, I just remembered the little graph looking thing but couldn't remember the exact temps...

but if you get 120+ * days I still would use 10w-30 in the summer...

 

if it were that hot i would, but my question is, what does it matter when the engine runs atleast 200 degrees anyways?

 

the outside temperatures will have a direct effect on the cooling of the engine. A engine running hard in 105 degree weather will be a lot hotter than one running hard in 50 degrees

the hotter air will not cool the water/coolant mixture or keep the underhood temps down as well...And this can have a direct effect on the condition of the engine's oil. It is just "safer" to have 10w in the engine in these heat ranges, but it is not that critical...

 

Thanks for the input. It all make sense, but how about my logic? Does anyone think my logic is flawed? If Mobil1 5w-30 indeed out perform dino 10w-30 under all temp and dino 10w-30 is good for the P5 engine in 120+ temp, shouldn't the Mobil1 5w-30 be even better? Yes, the Mobil1 10w-30 may provide even more high temp protection than it's 5w-30 counterpart, but M1 5w-30 should be more than adequate for our engines under all temp range, right?

 

??? not sure on that one, if it gets under say 20 or 30 degreees, then run 5w30, if it gets really hot like 115 or 120, then run 10W30. other than that its completely your choice. there is no real difference.

 

Ahhh,
the Moral of this Story:
Use Mobile1!
Personally, 10w-30 for me...

 

Well, I'll chime in.

I run (and plan to all year round) Mobil1 5w-30. Why? Because I've used it on many previous vehicles, and never had issues. Also, the nominal temp range in Ohio is 20F-90F. So this viscoscity (sp?) should be more than sufficient for my little 2.0L P5.

And think about this. The only real difference between the two (5w - 10w) is low temp (startup) viscoscity. After it's at NOT (normal operating temp,) they're both 30 weight oil, right? Correct me if I'm wrong.......

Jim

 

did you forget about the highest outdoor temp??

 

All I'm saying is that both are 30 weight oil at temp. If that be the case, then both viscoscities should have the same flash point, and the ability to protect the engine at any given high ambient temp (within it's range.) True??

Jim

 

the 5w30 can isn't supposed to be ran above 105 degree outside, thats the only reason to switch from 5w30 to 10w30

 

i always use Mobil 1 5w-30, i live in PA and it doesnt get much hotter than high 90's. I am gonna switch to redline 5w- 30 at my next oil change.