I'll give you a quick example of the savings synthetics offer. I have a diesel customer that I am good friends with. He has a commercial floor cleaning business and drives a Dodge 3500 with a 5.9L turbo diesel. He came to me and asked if I could help him out. With the amount of driving he was doing he was having to change his oil every 3 - 4 weeks. It was costing him around $45 to do it as well using regular non-synthetic motor oil so it was costing him near $550 a year plus the down time to get it done.
So I did a work up for him and using the best synthetic motor oil that Amsoil had at the time and an oil filter. That ended up costing around $150 for the oil and filter. We did an oil analysis on the oil at every scheduled filter change.
To make a long story short, he ended up getting over 60,000 miles out of that oil change before he decided to go ahead and change it on his own even though the oil analysis said he could go further. Between the oil filters and oil analysis he may have spent around $225 maybe $250.
So ultimately he was able to save about 50% on his maintenance costs and its even more now because we dont do an oil analysis as often. We did them more frequently to start so that we could establish a baseline for how long his oil drain intervals could be. That doesnt take into account the savings in time having to get in for an oil change about every month. He also picked up a couple miles per gallon in fuel economy too and with as much driving as he does, that translates into even bigger savings.
My Grand Prix alone I went over 15k miles on one oil change before the oil analysis showed I had a coolant leak from the LIM gaskets. Even then the oil analysis showed no significant increase in wear in the rod bearings or engine wear so I could have went even further, but I shorted my change intervals to 7500 miles until I got the LIM gaskets replaced. I pulled an oil analysis at those intervals and those too showed that I could have gone further but not knowing if the leak would get worse over time I chose to stay with the shorter change intervals.
Additionally, when I first got the Grand Prix I got 28mpg on a trip to Florida the week I bought the GP. I got back home and switched the transmission and engine over to synthetics. About a month after getting back I had to make an emergency trip back to Florida and I got 31.5mpg the whole trip.
I was in the 33 mpg range, all highway, when the differential went out on the GP. So if you take advantage of what a good, true synthetic motor oil has to offer, they can ultimately save you money in more ways than one.