My 99 Stratus is nearing 187k miles. It drives good and hardly burns any oil, but it's a bit noisy at startup and idle. I was using Castrol GTX 10W30 for years every 4k miles but the last oil change was Mobil Super Synthetic 10W30. The mpg economy got better but the engine noise is still there.
So I was wondering if a high mileage engine is better of with a different grade oil than the recommended grade for a new engine. I am in Austin, TX where it is always above freezing in winter and scorching hot in the summer.
I am leaning towards a higher grade like 15W30 or 10W40.
Any help would be appreciated.

 

The 2.5 starts cold at a rather high RPM. If it car has been sitting a while the bearings will rap for a second or two. I switched to Mobile1 Hi-Mileage 10w 40. That helps a lot. I now have a push button on the dash that disconnects the temperature sending unit and replaces it with a 1200 ohm resistor. I use it on the first morning start. It makes the computer think there is a warm engine. It slows the cold start revs. After the first start i find there is no need for the button.

 

Thanks for the response, but after doing other research I've decided to stick with Mobil Super Synthetic 10W30. I think a heavier oil would be an extra strain on an old engine.
When I was living in NY I tried a trick similar to yours to get better mpg, in fooling the ECU that the engine is warm, but it didn't work out to good.

 

You can try adding an additive like Seafoam. I use it on my work minivan at every oil change. When it was given to me, it had 120k miles on it and a loud knock. I assumed it was a bent rod or something and work wouldn't pay for it to get repaired. So I started using Seafoam, let the van warm up about 2 minutes before driving and no knocking/pinging going on.