I changed to 10-40W from 10-30W and it seems like I have less power now. Is this possible?

Thanks

 

No, unless you overfilled. Either will become the same viscosity when up to operating temp. It might crank a little slower when very cold, but that's the only difference I can think of unless you went from synthetic to dino too.

Otherwise, see if your fuel formulation changes to Summer formula on April 1. If so, the new blend might cut power.

 

Yes, pumping a 40 weight oil takes more power then pumping a 30 weight oil. However, the difference should not be substantial enough for you to detect by seat of the pants driving normally.

 

I ran a thicker oil in my Eclipse for part of a race season and going to a thicker summer oil di not have any effect on my 1/4 mile times so if there is a power loss it's negligible.

 

Hey Bob, I beg to differ on both points.

Oil viscocity works the opposite of what you are thinking. Both oils will have have the same low temp characteristics, that the "10", but at operating temperature, 10W40 is more viscous than 10W30, that's the 30 vs 40. As a result, there will be some increased drag at operating temperature, it's just not very significant. Many of us run 0W30 synthetic for the increased flow in cold temperatures. The "0" flows better than the "10".

See http://www.valvoline.com/carcare/art...0101ov&cat=ccr for details.

"Winter gasoline" otherwise known as "Oxygenated gasoline" tends to cause a decrease in both power and mileage. Many of us see a distinct decrease in both in the fall and a return of our normal mileage/power in the spring as a result of the oxenated gas being eliminated. See http://www.epa.gov/otaq/oxygenate.htm and http://www.chevron.com/prodserv/fuel...etin/oxy-fuel/ for details.

 

Rob, I see what you mean from the oil link! They use 100° C to measure pour rate where normal operating temps are usually much lower, around 85°C. I wonder how a 10W-30 would compare to a 10W-40 at a more normal, everyday operating temp. My thinking was that the -40 part wouldn't be effective until ambients exceeded maybe 100°F, like the bar charts usually printed on the oil container.

I use 0W-30 synthetic for road racing, where engine oil temps are well beyond anything seen during street use. I use it for the flow and cooling effect. I've compared it to 20W-50 synthetic, and oil temps are lower with 0W-30. Long term durability wasn't compared, the race cars were sold after a season.

Oxyfuel, it isn't just for Winter anymore. The link is dated 2001, but the latest EPA mandates impose oxy blends for Summer in certain jurisdictions. I read (no link handy) that there are over two dozen blends nationwide, sometimes several per state, and the oxy blends could be either Winter only, Summer only, or year 'round depending on where you live. A political twist is Oregon where although the entire state is EPA compliant, the former governor "volunteered" us to use oxyfuel all year anyway, adding cost while decreasing performance and fuel economy.

 

I hate that oxygenated gas We have been lucky here so far, the summer gas continues to be better fuel than the winter. As a result, I see a significant spike in my mileage and power every spring Hopefully that trend continues and we don't followin the footsteps of those communities that have decided that crappy mileage and performance are key to air quality

Oil wise, those graphs are available on the net, sorry I don't have a ready link and have to run off to a meeting. But, if two oils start off at 10 and one has a warm rating of 30 and one of 40, you can draw a pair of lines from 10@0 to 30/40@100 and see what the viscosity is going to be at a given temperature. The polymer chains that uncoil to increase viscosity as temperature rises do so in a very predictable way and at a very predictable rate.

 

is april 1st normally when they switch back to the summer formulation?

 

Depends upon the state. Here in CO we run ethanol gas from Nov. 1 to Mar. 1, and many run it all year long due to the costs of switching blends.

 

Well I changed back to 10-30W. I must say the 4runner feels much better now. So, I guess the weight of the oil can have an effect on the power.

 

Hi
I always stick to what your owners manual suggest. I use 5w30.