In the Volvo 855. After the 20K, I just went about 5K miles with the ASL 5W-30 (didn't do a sample for UOA). The Amsoil 10W-40 (AMO) is in the same basic construction category as the ATM (10W-30) and ASL (5W-30) as far as I can tell. Same price. (cost me just under $4.50 qt) Anyhow this is the first time this car has seen synthetic XW-40. I can say the idle is more quiet. Interesting. I will run it 5-10K miles and do a UOA. Using a Mann (Volvo OEM) OF.