I bought a bottle of VWB 10w-30, a bottle of VWB 5w-30, and a bottle of Delo 15w-40. I put them in the refrigerator and got them down to about 42 deg. F. When shaking the two grades of VWB, they were still relatively "watery". They both poured easily, with the 5w-30 being just thinner enough to notice. Not much difference. The 15w-40, though, was much thicker, feeling very different on the "shake test", and pouring noticeably slower.
Then I put them all in the freezer and got them down to about 0 deg. F. All were thicker, of course, but the VWB grades still poured pretty well and passed the "shake test" as far as I was concerned. Still not a whole lot of difference between the VWB grades, but enough to notice. The Delo 15w-40, on the other hand, was thicker than molasses and didn't shake too well. Poured very slowly.
The purposes were to see if 10w-30 would be a good year-round grade for southern California, and also to see the difference in an HD 15w-40.
My conclusion is that in southern Cal., either 5w-30 or 10w-30 would be fine. I have an idea that in an engine that burns a little oil, the 10w-30 might be better. If temps get very far below freezing, the 5w-30 would pump a little faster. Secondly, in VWB, there's not a great deal of difference in moderately low temp. performance between the 5w-30 and 10w-30. The 10w-30, however, has a much lower NOACK number.
My other conclusion is that if I use HDEO, I'd rather use 10w-30 under almost any conditions than 15w-40. The exception would be constant Death Valley type heat. For summer use in LA or San Diego areas, I figure the 15w-40 would probably be OK, but not my first choice unless I were doing a lot of towing or something like that.
Disclaimer: All of my vehicles have pretty high mileage and are out of warranty. If any were in warranty, I'd use whatever viscosity grade the warranty calls for. My vehicles all call for 5w-30.
Then I put them all in the freezer and got them down to about 0 deg. F. All were thicker, of course, but the VWB grades still poured pretty well and passed the "shake test" as far as I was concerned. Still not a whole lot of difference between the VWB grades, but enough to notice. The Delo 15w-40, on the other hand, was thicker than molasses and didn't shake too well. Poured very slowly.
The purposes were to see if 10w-30 would be a good year-round grade for southern California, and also to see the difference in an HD 15w-40.
My conclusion is that in southern Cal., either 5w-30 or 10w-30 would be fine. I have an idea that in an engine that burns a little oil, the 10w-30 might be better. If temps get very far below freezing, the 5w-30 would pump a little faster. Secondly, in VWB, there's not a great deal of difference in moderately low temp. performance between the 5w-30 and 10w-30. The 10w-30, however, has a much lower NOACK number.
My other conclusion is that if I use HDEO, I'd rather use 10w-30 under almost any conditions than 15w-40. The exception would be constant Death Valley type heat. For summer use in LA or San Diego areas, I figure the 15w-40 would probably be OK, but not my first choice unless I were doing a lot of towing or something like that.
Disclaimer: All of my vehicles have pretty high mileage and are out of warranty. If any were in warranty, I'd use whatever viscosity grade the warranty calls for. My vehicles all call for 5w-30.
