Was driving my S70 Glt the other day down the highway. It was very muggy and hot. I had all the windows open and could no longer handle it any more. I closed the windows and turned the air conditioning on bust. Heavy mist/fog came out of the vents. The air was ice cold. Is there a leak, or is this normal? Also, I have always used Castrol oil for my engine. I read somewhere about AMS oil and decided to try it after a rear main seal repair. I used to get around 500-550km on a tank, and have since noticed I am getting upwards of 700km to a tank all highway. Can oil make a difference like that? (I regularly drive from Morgantown VW to Toronto which is 620km and did the trip on one tank and had 30 liters left with the ac on most of the time!!!)

Thanks

I had fog pass through the vents of my S70 yesterday just as you describe. I had been running the AC at max for a while and switched it off for a moment as I merged onto the 401. Once the car got up to speed I turned the AC on again and an odourless fog briefly streamed out all the vents. I'm certain it was just condensation due to the temperature change, but at the moment it happened I thought it was freon or smoke.

I'm guessing that the misting stopped after a few minutes of AC usage. Your ducting had a lot of humid air in it, and the blast of cool air caused condensation. I would appreciate an update on your exact milage increase over several tanks of gas. I wouldn't have thought AMSOIL or any oil could make a noticable difference.

"Fog," under those conditions, sounds pretty normal to me.

Fuel economy can vary tremendously, based on a number of factors. I have little doubt that your observations of distance per tank are accurate, but you're likely missing such details as average speed, climate/season, city vs highway driving, tire pressures, etc. For what it's worth, I've experienced as much as a 1.5 mile per gallon (about 0.6 km per liter) difference by changing from dirty, heavy weight, non-synthetic oils to light weight synthetics.

BTW, I'm sure this site will help, if this thread gets drawn out:

http://www.onlineconversion.com/fuel_consumption.htm



--
Jim Rothe, '99 S70 T5M,
http://www.jimrothe.com/volvo/index.html