If you thinking about 1 oil change per year, 100 miles a day is 500 miles a week is 25,000 miles a year (2 weeks vacation a year), then Amsoil SS is perfect match for your wife driving condition.
If you like to change oil twice a year then Mobil 1 Extended Performance is a better choice for its lower price and up to 15,000 miles OCI.
Either case you like to buy the high-end oil filter if you like to do either 6 mo or 1 year OCI.
I would use regular synthetic 5w20 and a wix filter although my number one choice for ford filters was motorcraft they are made by purolator and their quality got baddd
change the oil 1 year or 6000 miles
I haven't been impressed with Amsoil SS UOAs. If you were to use it, you should get UOA's to prove it can go the distance. Same holds true for any extended oci.
Be aware that the cold performance of oil degrades over time. Seeing you are in Michigan, I would aim to do my (annual or semi annual) oil change before winter.
I have run Amsoil for 19 years and think it should work fine for running longer intervals for your vehicle. I think it's worth the money.
I've run different dino oils. Then started using name brand synthetics when they were getting popular in the 80s. Settled on Mobil 1 so I would not have to change as often. I then switched to Amsoil a few years later.
If you run the oil out a ways you will get your money out of it. One of my big things is having family vehicles that I maintain. So running oil farther out helped me to not have to work on changing oil so frequently. I want to use some of the best oil I can get my hands on, and run it out a ways. I decided a long time ago I did not want to buy cheap oil and change it often. I like to minimize being on my back under cars.
I just bought a 2008 lincoln mkz 8n great shape for my wife who drives over 100 miles a day. And am considering using Amsoil oil and filter. Is it worth $$$
Yes, it's worth the money if you can use it to its potential. Extending your OCI using UOAs is the only way to be sure (true with any oil).
I'd start with a baseline UOA at the factory OCI, leaving the oil in and extend from there. Blackstone is usually conservative about their recommendations, so then you could do the same test at their recommended additional mileage, and so forth. Then once you've figured out how long the oil can safely go with your wife's driving style, you can make the decision as to whether to continue with Amsoil SS or not. So if your engine is easy on oil, Amsoil will save you $$ and time in the long run.
I'm an Amsoil fan/user, but even so if your engine breaks down oil quickly there's no reason to try to extend your OCI and you would be better served using an inexpensive oil....such as:
Originally Posted By: Pablo
If you aren't doing extended changes, get Amsoil OE 5W-20 (Product Code OEM) and save money over Mobil 1.
If you don't like Mobil 1 EP you could run Castrol EP (gold) which also claims to be good for "up to 15K".
If the price of these 2 EP oils was the same I'd probably run the Mobil EP.
*Since your wife drives 100 miles a day I'm assuming it's predominately highway miles...in this case any good synthetic (QSUD, M1, PP, VSP etc) should be able to handle it changed every 6 months.