Is it safe to follow the oil manufacturer recommendations? I think Mobil says to replace the syn oil every 14-15k miles but I'm paranoid and always replace it at around 10k miles.

 

Years ago, I was at an industrial expo and a Royal Purple Rep was there. He said to change it every 14k and the filter at 7k and top it off. I used to change the wife's tahoe's oil and filter with RP every 10k just because it was easy to remember. Used a WIX filter. I got cheap and went back to Rotella 10w30 whenever the life change meter says.
It's an 04 LS Tahoe and it just says to change and no % life. My 05 truck is the same. I think it has to do with what trip package you have for how much detail. My brothers 02 Denali has the oil life as well as fuel mileage meter.

 

Guys, I have been using synthetics since around 1989-1990 and started using Amsoil back in 2001.
First of yes the oil minder is based on mathematical equations that take into account the driving conditions as stated, however with a little knowledge and some forethought one can see certain faults in the logic of completely relying on it. It can be a good tool IF you use the equivalent oil they use and keep your truck stock.
In the Corvette Forum there is an engineer that worked on the development and he stated all the things they looked at when coming up with the system, which BTW where quite extensive including engine metallurgy, oil qualities, and driving conditions, good now I will tell you the other side.
Oil products are not created equal and there is guarantee that even the original formulation will be kept the same. The lubricant is made up of two parts a base oil, and an additive package and they are both important to the performance of the lubricant. The base oil stocks whether mineral oil, or synthetic may be similar but not the same necessarily, and likewise for the additive package. The job of the additive package is to protect the base oil, and after it is spent the base oil will deteriorate at a much faster pace.
The problem I see with the oil minders is that they do not test the oil, and therefore do not know the oils true condition. Even if you use the same oil and kept the vehicle stock it cannot tell you if you have dirt ingression from a faulty seal on the intake tract or a coolant leak for example. Both of those can cause the oil to deteriorate and or equipment wear or damage.
I will tell you that in my 2000 Alero 4 cyl. the Amsoil 5w-30 was good for ~32,000 miles without doing anything to it other then that I uｓe a bypass filter system. The filter system is very important because it keeps the oil clean by removing contaminants and allows both the oil and equipment wear to be minimized. The reason I know is because I installed a 25,000 mile full flow oil filter along with a 65,000 mile bypass filter and my Alero did not use enough oil for me to top it off (~1.5 quarts in ~32000 miles, topping off oil allows one to replenish the additive package). As I tested the oil the additive package breakdown was apparent over time, and in the last interval the breakdown went down much faster.
On my Silverado I also used a bypass filter system but used different filters and it allowed me to top off the oil on the average of ~5000 miles and the additive package of the same Amsoil stayed at a usable rate for around twice that life cycle. :nunchuk1:
On the Alero I decided to try Q-Power and Penzoil and still using a bypass filter neither had the life cycle range of the Amsoil. I am not knocking them they are cheaper oils to buy, but you do get what you pay for. Something else is that not every vehicle is the same so on some vehicles the same lubricant may not have the same life cycle. My wife’s Trailblazer is like that it runs much hotter then the Alero, or Silverado and the same Amsoil has a shorter life cycle. My testing of the oils has given me information for some different approaches to maintenance strategies but I will save those for another post if you guys are interested as this post is already very long.

 

Long but good info.