Many cars and trucks now days are using a 20w oil. I'm assume that is to reduce engine drag, increasing gas mileage. But, is it also causing your engine to wear faster than running a heavier oil like a 30w or a 30w-40 oil?
Many of today's cars are using 5w-20 or even 0w-20.
In the fifties I worked in auto service and owned cars myself.
We used 20 in the summer and 10 In the winter.
Some worn out old cars were using 30 in the summer, but most folks either stayed with s.a.e. 10 all year or switched to 20 for the summer.
When 10w-30 came out I would say half of the folks went for it, the rest stayed with 20 or 20w-20.
I have seen 5w-40, 10w-40, 15w-40 and maybe 20w-40. I have never heard of 30-40, or 30w-40.
Have you noticed the cars that run several hundred thousand miles without overhaul have been doing it on 5w-20 and 5w-30?
Yes Aaron your correct. work for a local honda dealer and people coming in for service have 100's of thousands of miles. Only real problems is when they don't do the oil changes.
I think for us it is more about the make up of the oil.
I use a mineral Diesel oil in my vintage cars for the high zinc content.
Some years ago I used a 10w/50 full synthetic diesel oil in my 6.5 Chev diesel. The result was a rattling oil burning mess. I was convinced I needed a rebuild but a change back to 20w/50 mineral diesel reversed the situation instantly.
Heavier oil is not better oil. Today's cars typically will run 250,000 miles or more before they start using any oil between oil changes. The reason these new engines last so long is mostly because engineers have refined their methods of oil control and improved oil manufacturing technology.
The key to engine longevity whether it is a Model T or a 2016 Ford Taurus is keeping the engine oil clean, and using appropriate oil for the temperature conditions.
Cars from the 1960's - 1970's were designed for 10W-30 oil in summer time driving. Many were ruined by folks who ran thicker oil, believing they knew something that engineers did not.
Royce is correct in large measure, but one of the key reasons for extended engine lifetime and reliable service are a combination of cnc machining, new alloys, and better quality components. CNC machining has allowed engines to utilize lower viscosity blends due to tighter uniform tolerances. Alloys have given given rise to longer lasting metal components that resist wear better, and certainly better quality components has helped tremendously. I don't remember an engine manufactured back in the 70's that made it past 100K miles without having the valve seals leak copiously and the engine oil pressure falling while at idle unless you ran that thicker oil. We are fortunate now to have so many choices of quality lubricants that fit about anyone's budget. Considering the glop that Model T owner had available in the day, our old cars have to be thrilled with the lubricants we're feeding them now.
My 2008 Camry takes an oil change every 5000 miles, which I did just yesterday. It's now at about 147 K and I've never had to add a drop between changes. The book calls for 5W-20, so that's what I put in it.