Date: Sun, 12 Jan 1997 11:17:21 -0800 From: Mike West <mwest@cdsnet.net> Subject: Re: 30W & zero temps & battery >> I just had my 77 camper engine rebuilt. The shop that did the work >> strongly recommends 30W oild for air-cooled engines. The temperture is >> hovering around zero and my camper doesn't want to start. Some of the >> problem is attributable to a balky battery that goes from 12.3 to 6.5 upon >> starting. <big snip> ---------------------------------------------------------------------- I think it's a reasonable assumption that you need a new battery with some decent Cold Cranking Amps or even a second battery. CCA is supposed to mean the cranking amps at "0" degrees F. Don't bet your life on it tho. There are a number of things you should look at first and they are all electrical contacts and grounds. Check them at the cold time. At "0" degrees, there is very little chemical reaction going on any where in the world. That's why food stays relatively fresh. It is no different in your battery. Old memory tells me a 30% efficiency at that temp. (don't quote me) You have a fresh rebuild and if they did it right it's a relatively tight engine right now. The cold just makes it tighter. Third verse: Multi-viscosity oils are tested at 10 degrees above their rating (more old memory cells) meaning that 10W is tested for viscosity at 20 degrees. That means the oil will flow thru an orfice I can't remember size in 10 seconds. The size of the orfice is the "Saybolt orfice". So the viscosity is ten "Seconds Saybolt Universal". SSU. That 10W is supposed to mean it can be run at 10 degrees F. The other number as in 10W-30 means it will have a comparable viscosity to 30 weight at 180 degrees. (old mem cells) Above the 180 they go to hell in a hurry and won't compare with single weight oils. If I could get 5W-30 or 40, I would probably use that at those temps and with your problems. If your oil light starts flickering at you at operating temps, then you've gone too far and you need to thicken the oil up some. west