Absolutely go with whatever any manufacturer suggests for the life of an alloy frame.

I have a book from 1981 called Bicycling Science which was published in England, it is full of all sorts of engineering data and charts etc.. It gives the characteristics of the different bicycle frame materials including aluminum and steel, and it says that for an aluminum frame to be as strong and reliable as a steel frame, it has to have enough aluminum in it so it will weigh as much as the steel frame. But even if that were the case I would still not trust aluminum because unlike steel it can not bend like steel can, then spring back into shape with no loss of life expectancy. If you bend a piece of aluminum with your hands then bend it back two or three times you can break it in half, but with carbon steel with the right heat-treatment you can bend it back and forth almost infinitely.
I bought a steel-framed mountainbike 25 years ago and still ride it hard, but I have replaced the alloy bars and stem with steel items, and the alloy seat-post is next for replacement with a steel item, or steel reinforcement.

My guess is that aluminum bicycle parts exist partly as marketing tools, and partly because aluminum is easier on the stamping and forging dies than steel is. But according to the engineering, it is 100% possible to make a bicycle out of steel that is just as light and at the same time more reliable than out of aluminum. Also, I weight over 200 pounds, so I am extra wary of the life of bike parts. A lot of things may take me out, but if I can eliminate one variable by going with steel I will do it.