em14 said:
SkyPup,
How can the change internals be extended if the Synthetic is picking up the "Dirty" deposits conventional Dino oil is. So if the change period is close to the same why use the more expensive Synthetic in low speed engines such as a Diesel. I can see the need if it is used in high speed and / or high heat machines since it doesn’t break down at the higher heats like the Dino oil does. Not trying to be confrontational just trying to understand.
Thanks
Leo
Here's how I have seen it work first hand. I have been a diesel mechanic for years and more recently am in the process of getting out of the repair business and going into lubricant sales (it's easier on the body). So I have had thousands if not 10's of thousands of gallons of oil pass through my hands over the years.
Many years ago I was one of those mechanic's that suggested to my customers to change their oil at the manufacturers recomended intervals. Did that for quite a long time to with no problems, oil related that is.
Luckily I was alway's the inquisitive type and at one point started doing some research on tribology (the science of lubricants). One thing I quickly learned was that the OEM's recomended service intervals were (how should I put this) useless. No two engines operate in the same conditions, enviroments, under the same load, etc... All the variables greatly effect engine oil life. A truck working in a coal mine that is a very dusty enviroment may end up with oil change intervals 1/10 or less of what you can expect from a OTR truck/tractor. This is where UOA's (used oil analysis) comes in.
After discovering UOA's I started to search for suppliers I could buy my bulk oil from that included UOA's at no cost. There hard to find but there out there. In any case I started to do UOA's on all of my customers trucks and found that on heavy road tractors that had been on a 10K or 15K mile OCI (oil change interval) they could now easily get 25-30K or even more with proper testing. One thing I did quickly find out was that the oil needed to be changed not because of soot contamination but in most cases due to TBN dropping off close to the end. A very few showed fuel dilution and others yet had high dirt contamination levels due to the conditions these trucks were in. It all depends on each exact truck and it's operating conditions.
In my experience TBN reduction was the main cause to change oil. Not that the oil was contaminated and dirty but because it's additive package had become depleted. After a few years of experiementing I found that the higher quality of oil that I used the longer the change intervals could be extended. However I did find that there is a point with each truck that no matter how high a quality oil you use in it, it does eventually become soot loaded and needs to be changed. The higher quality engine oils had better additive packages and did increase OCI's over regular off the shelf oil but only to a certain point. What I ended up finding was that semi-synthetic worked best for me. The oil and additive package could easily last long enough, to the point where the oil needed changing due to contamination. I found the use of full synthetic's was not really needed as the oil became contaminated long before the base oil would shear down to the point it was worn out. With the high quality semi-synthetic and even premium GPII dino oils I and my customers got the best bang for the buck.
A few customers trucks I worked on did have oil bypass filters on them and these trucks normally got longer change intervals due to a large majority of the contaminates being filtered out. OTR truck that would normally have a 40 quart oil capacity and with the Luberfiner bypass filter system on them had their oil capacity increased another 16-20 quarts and the OCI's were safe out to about 100K in most cases.
So is there anything wrong with the factory intervals. Only that they end up consuming more natural resources (oil) and in the long run end up costing you more because your changing your oil more often than it needs to be.