> > From: Joseph Tainter <[EMAIL PROTECTED]> > Date: 2008/02/10 Sun PM 06:39:14 GMT > To: pdml@pdml.net > Subject: Follow-Up OT: Question for Pentax Auto Buffs Discussion Group > > Thanks everyone for the replies to my question about 5W-30 oil. Now I > understand. > > A couple of you sent replies like this one from Paul: > > "At one time powerplant experts thought that wider bearing clearances > and heavier oil offered optimum protection. Eventually they discovered > that lighter oils and tighter clearances resulted in less wear, better > power and better fuel economy. What's more the 10W-40 oils sometimes > caused sticking of rings under some conditions. Not good." > > Does anyone know when this change in engine design took place?
Not so much a change as general progression of improvements. > > My 1989 Volvo 740 has 230,000 mi./370,000 km. and burns no oil. I have > been using Castrol synthetic 10W-40 oil in it year round. Should I > switch to 5W-30 or continue with the heavier oil? > > My wife was advised to use 20W-50 in her 1967 Austin-Healey Sprite. > Should she change to something lighter? As both engines have plentiful supplies of spares, there is no reason not to try. 8-) If you do, I would suggest regular attention to oil levels and a frequent check of tappets for the first few thousand miles. As these provide a measure of a high-stress part of the engine, any sign of loss of stability in the measurements should be a call to revert to the previous type of oil. You may find that the oil pressure light takes a fraction longer to go out. This is nothing to worry about, just don't touch the accellerator until it does. ----------------------------------------- Email sent from www.virginmedia.com/email Virus-checked using McAfee(R) Software and scanned for spam -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
