Highest interval I have on my business fleet is 50k km (31k miles) with a filter change half way. I run Amsoil SS 0w20 in everything and cheap filters (usually Pronto) from Rock Auto. It's a bit of a special case though since these vehicles do 100% highway and can accumulate 50k in a few months. I recently bought a couple Honda Odyssey vans and had to cut the oil change intervals in half because the engines are brutal on the oil.
As for the Cobra I think I've settled on changing the oil every 2 years. The sump holds an entire case of Amsoil Racing 10w30 and I would do less than 5000 miles in those 2 years so I'm sure it's safe.
As for the Cobra I think I've settled on changing the oil every 2 years. The sump holds an entire case of Amsoil Racing 10w30 and I would do less than 5000 miles in those 2 years so I'm sure it's safe.