konak85

iTrader: (10)

Just got my Max not too long ago. I was thinking of using 5w-30 engine oil during winter and fall and using 10w-30 in summer and spring. Is it okay to frequently change the type of oil frequently like this or is it harmful? Any precautions?

matty

iTrader: (54)

I do it...5W-30 for the winter and 10W-30 for the summer...your right near me and I Have the same thing on my mind as you, starting that car up in the mornings we have had recently is on my mind alot...
Do it, but definetly use synthetic as well...it helps on those cold mornings

-matt

Torkaholic

A perfectly valid approach, especially where you're changing from one recommended grade to another.

CCS2k1Max

iTrader: (2)

For whatever is worth, 10W-30 grade is contained within 5W-30. It's already there. One thing would be going up to 10W-40, which isn't in 5W-30, but 10W-30 is already in 5W-30. The only advantage would be less additives than 5W-30.

Per the owners manual: "SAE 5W-30 viscosity oil is preferred for all ambient temperatures. SAE 10W-30, 10W-40 viscosity oil may be used if the ambient temperature is above 0°F (−18°C)."

Torkaholic

As far as the grades themselves numerically, that's correct. And with respect to the dinos particularly, the 10w-30 would be expected to use less of the VIIs than the wider spread oils. That's less of an issue with the syns though, since they achieve basic vis properties as much via base fluid blending as through "additives." For example, compare the Mobil-1 5w-30 and 10w-30 grades. Yes, technically, the 10w falls within the parameters of the 5w, but if you look at the specific properties of the 10w, you can see that it's actually a different fluid. It shows a high-temp/high-shear viscosity (HTHS) of almost 3.2, whereas the 5w-30 has an HTHS of only 2.9. Thus, to get the better cold flow of the 5w, you do give up some of the HTHS performance that the 10w can give you. Which is "best," of course, depends upon the application and the owner's preferences.

CCS2k1Max

iTrader: (2)

Then, if what you really want is higher HT/HS, I'd stop messing around and upgrade to 10W-40 and get noticeable HT/HS increase while still staying within factory specs.

Torkaholic

Yeah, but I want to have my cake and eat it too. The 0w-30 German Castrol has a 3.6 HTHS, and has demonstrated near-phenomenal results in a wide variety of platforms. No, this grade is not spec in the VQ manual, but on the other hand, I see no way in which using a 0w-30/40 oil could harm a VQ either. A cold 0w-x oil is still going to be thicker than even a hot 40 or 40, so it's not like the 0w-x is a fluid that's much wildly different from what the engineers spec-ed for the car. Going to the 10w-40 would keep me "in the book" and give me much higher HTHS, but I'd have to trade away the great starting oil flow that a 0w should provide. I'm pleased for now with my UOA from the GC, but continuing to monitor.

CCS2k1Max

iTrader: (2)

Now you're getting OT since the original question was switching between 5W- and 10W-30 (I'm assuming dino here since he didn't specify). The answer to the original question should be use Mobil1 5W-30 and stick to it year round.

p.s. where do you get the green Castrol?

Torkaholic

Guilty as charged. . . I guess to bring it half back on target, I'd recommend using the 0w-30 GC over either 5w-30 or 10w-30, generally. Back OT, the only place I've found the green elixir of engine life is at Autozone stores. You have to be careful, though, as there is a fair amount of old US-made Syntec out there, and they're often stocked together. GC will have the "0w-30" block outlined in red ink (the US made is yellow), and on the back, look for the magic words, "Made in Germany". It will also say "Castrol North America" nearby, so don't be misled. If it says "M.i.G.", it's the real thing. There are rumors that Castrol has resumed US production, and that the new US stuff has the red label, but I have not seen any of this. Bottom line is: 1) GC is only at AZ in the US (Walmart too in Canada), and 2) it must have "Made in Germany" on the back.