Hmm...
I have worked for a lot of shops and by far the most expert mechanic that I have ever worked for and one of the best I have ever met had something to say similar to the last post: appropriate viscosity is better.
He had certain reasons and logic behind this which I will do my humble best to layout in the few spare minutes I have before I catch my plane to New England.
The first thing I think he mentioned about it was that the manufacturer recommends a certain viscosity for a reason [whatever that reason may be].
As a shop owner he did his VERY best to stick by manufacturers recommendations for most things and was smart enough to USUALLY know when there was something better to do.
Another very important point he mentioned was liability. If you do your own oil changes you do not have to worry about this. He MADE me read the book from the oil supplier for EVERY car and use the recommended viscosity. In a small shop one needs to cover their legal bases the best one can and still do the best job on believes possible.
I believe the very most important thing that he said to me on this topic had to do with the size of oil passages. I may have missed this in this thread but I did not see it. When I was young[er] and dumb[er] I used 20w-50 in a ford 2.3L in the winter and I remember hearing the hyrdaulic valve lash adjusters clack for at least 30 seconds after startup. What does this mean? Well,if I have to tell you... At that same ambient temperature however I believe certain years of Audi almost insisted on 20w-50.
Steve that owns Automasters in Meriden, CT is the ONLY mechanic I recommend friends and family bring cars to. I no longer live in that part of the country so I cannot fix their cars. When I worked for him we had many many customers over 200K and 300K on their vehicles. I was asked once by another shop owner if I changed a lot of transmissions when I fixed Saabs [at Steve's largely Swedish vehicle shop] and I replied that I had changed very few. He was very surprised. This got me thinking. We had relatively few major failures compared to many shops in the area. Our preventative maintanence was good. We used the recommended fluids including special transmission fluids for Honda and Chrysler. We usually did what the manufacturer said and I think our customers did right by us.
We used the recommended viscosity. This is not always perfect, it depends on the manufacturer to do their homework. They have millions to figure this stuff out with while we have to all decide who and what we will believe. If liability is an issue I'd stick close to the recommendations. If you are a DIYer, do what you will.
The design of the oiling system and size of the oil passages makes proper, err, umm, appropriate viscosity selection important. If thicker is ALWAYS better then put some gear oil or grease in your sump.
That being said, I do agree with TallPaul that a thick film is desirable. I think thicker IS better IF the oiling system is designed for or can handle it. If you have an oil pre-charger and block heater installed MAYBE thicker is always better. It is accepted that the majority of engine wear occurs at cold startup, right?
On those vehicles which have different recommendations in different countries for the same engine, I wonder which one will last longer...
What I want is for my oil to circulate instantly and for it to protect very well under heavy loads or abuse. I want it all. Do I know how to get that? Well, no. I know how the best results I have ever seen have been obtained and I am humbly relaying that data here.
I have worked for a lot of shops and by far the most expert mechanic that I have ever worked for and one of the best I have ever met had something to say similar to the last post: appropriate viscosity is better.
He had certain reasons and logic behind this which I will do my humble best to layout in the few spare minutes I have before I catch my plane to New England.
The first thing I think he mentioned about it was that the manufacturer recommends a certain viscosity for a reason [whatever that reason may be].
As a shop owner he did his VERY best to stick by manufacturers recommendations for most things and was smart enough to USUALLY know when there was something better to do.
Another very important point he mentioned was liability. If you do your own oil changes you do not have to worry about this. He MADE me read the book from the oil supplier for EVERY car and use the recommended viscosity. In a small shop one needs to cover their legal bases the best one can and still do the best job on believes possible.
I believe the very most important thing that he said to me on this topic had to do with the size of oil passages. I may have missed this in this thread but I did not see it. When I was young[er] and dumb[er] I used 20w-50 in a ford 2.3L in the winter and I remember hearing the hyrdaulic valve lash adjusters clack for at least 30 seconds after startup. What does this mean? Well,if I have to tell you... At that same ambient temperature however I believe certain years of Audi almost insisted on 20w-50.
Steve that owns Automasters in Meriden, CT is the ONLY mechanic I recommend friends and family bring cars to. I no longer live in that part of the country so I cannot fix their cars. When I worked for him we had many many customers over 200K and 300K on their vehicles. I was asked once by another shop owner if I changed a lot of transmissions when I fixed Saabs [at Steve's largely Swedish vehicle shop] and I replied that I had changed very few. He was very surprised. This got me thinking. We had relatively few major failures compared to many shops in the area. Our preventative maintanence was good. We used the recommended fluids including special transmission fluids for Honda and Chrysler. We usually did what the manufacturer said and I think our customers did right by us.
We used the recommended viscosity. This is not always perfect, it depends on the manufacturer to do their homework. They have millions to figure this stuff out with while we have to all decide who and what we will believe. If liability is an issue I'd stick close to the recommendations. If you are a DIYer, do what you will.
The design of the oiling system and size of the oil passages makes proper, err, umm, appropriate viscosity selection important. If thicker is ALWAYS better then put some gear oil or grease in your sump.
That being said, I do agree with TallPaul that a thick film is desirable. I think thicker IS better IF the oiling system is designed for or can handle it. If you have an oil pre-charger and block heater installed MAYBE thicker is always better. It is accepted that the majority of engine wear occurs at cold startup, right?
On those vehicles which have different recommendations in different countries for the same engine, I wonder which one will last longer...
What I want is for my oil to circulate instantly and for it to protect very well under heavy loads or abuse. I want it all. Do I know how to get that? Well, no. I know how the best results I have ever seen have been obtained and I am humbly relaying that data here.
