[DEWFPO]

The only advantage of synthetic oil is you can run it for extended periods.

Let's not forget temperature extremes. The synthetics do hold up better in very harsh, high heat operating conditions and do flow much better in sub zero temps. BTDT, ran dino and synthetic in those conditions and there are very noticeable differences.

DEWFPO

 

[DEWFPO]

So being in a climate where temps change 40+ degrees in one day, what do you suggest for a 95 suburban 4wd (160,000 miles) and 07 saturn aura (60,000 miles)?

That type of temperature swing is normal and not anything to worry about on a day to day basis. For me, it's the lowest and highest temperature I will be cold starting and operating my vehicle/ equipment in. For me, -20F to 100+F and I run either a 5W40 or 0W40 synthetic in all my vehicles/equipment year round. But that's me.

DEWFPO

 

[DEWFPO]

It was 17 below 0 here a few years ago. The 5-30 Castrol popped my oil gauge right up and I was focused on it.

I agree synthetic oil has it's advantages. My 2010 CTS requires Mobil 1 and that's what I put in it.

I notice the biggest differences on very cold starts with engines that have inverted filters like my '07 FJ or horizontally oriented filters that drain oil out overnight or over a few days. On vehicles that have the 'proper' oil filter mounting (where the oil filter is always chock full) it seems to be much less an issue.

DEWFPO

 

[DEWFPO]

OK - now that we've got the obligatory warning by someone who doesn't understand viscosity ranges & how they work out of the way - has anyone who does understand actually used the M1 0w-40 Euro spec oil I mentioned? Is Jayman still around?

Thanks!

Jayman is still around and is the best qualified to answer this for you.

I have been using the M1 0W40 in my '07 (spec'd for 5W30), and the engine seems to love it. The engine is definitely quieter and I've got no oil usage at 73,300 miles. I have not done a UOA on it, but I do run it to 10K with an Amsoil EaO oil filter.

DEWFPO

 

[DEWFPO]

For my specific operating conditions I run either M1 0W40 or AMS 5W40 with AMS Oil Filters on my '07. I've been very pleased with these two oils. In the past I've also used 5W30 and 0W30 synthetic oils as well, but like the first two I mentioned a little better.

DEWFPO

 

[DEWFPO]

I live/travel in an area where it can go to -20F in the winter and 105F in the summer. My '07 is spec'd for dino 5W30 at 5k OCI's but I've used synthetic 0w30 for a while and then 0W40 for the last 6-7 years at 10K OCIs. The engine still runs like new.

DEWFPO

 

[DEWFPO]

"High in the Rockies" of Colorado. 7,100' to be exact. The FJ's just under 137k miles. Still on the original Panasonic battery and brake pads. Amazing. It's my first Toyota and I'm truly impressed.

DEWFPO