In my '00 S2000 I always used Mobil 1 5W-50 - since 1000kms, to be exact - with no problems.
Now I'm considering the Castrol TWS 10w-60 for my '05.
Any opinions???
Thanks.

 

If you live in Death Valley, it might work. Otherwise, read your owners manual to see what Honda recommends for your climate.

 

I think you've been lucky so far. With a 50 weight oil, your oil pressure would be dangerously high. Seals may have broken and you just never knew it. Unless you track the car and are willing to do several warm up laps at lower rpm to get the oil heated up, using this sort of viscosity for daily street driving is unnecessary and possibly playing with fire.
If anything ever happened to your engine with this kind of oil in it, you may be SOL for warranty. But, it's your nickel.

 

Read the oil data posts .