Cold starting 5w30 to a 5w40

[Camprunner]

Im running Shell Rotella T Synthetic 5w40 in my 06 V6 Toyota 4runner and I was wondering is there a big difference between the drag on my engine at start up between a 5w30 to a 5w40? I don't notice any change upon starting. Im only running the 5w40 for the summer and the hard towing im doing pulling my camper I thought it would be worth a try.

 

[D-Roc]

I was certain that all 5 weight oils were tested at the same temps...?? Might just be minor differences between brands. I checked a few pdf's for 5W30, all seem to be tested at -30C, but then a few 5W40 pdf's had the oil tested at -25...

I'm sure another member has more accurate info...

 

[MGregoir]

The limits are based on -30 for cranking, -35 for pumping, but the old standard tested at -25, so it will have to meet the same limits as the other oils but they may only publish the -25 data.

 

[hominid7]

Interesting question. I would think a lot depends on what the 5w30 oil in question is, and if it is synthetic.

While all 5w's meet a specific criteria at a specific temperature, some do it better than others.

 

[Gary Allan]

Go to the 2nd link below the chart and plug in 4 oils ..5w-20, 5w30, 5w-40, and a 5w-50 using their spec sheets.