R34 oil and timing belt change

[drifter17a]

Have a forged r34 using 10w60 mobile 1 running around 700 mark fly. 
 

i only used it 200 miles since last march when oil and filter was done. Now I will be using it more often and set to change oil and throw away what I had opened from last year.

 

Question is, does oil setting on shelf for a year or so breakdown or even few years?

 

how about sitting in engine?

 

engine rebuild will be a lot more costly hence why I change it every 12 month and wanted to get some opinion

 

question 2 is around timing belt, was done 4 years or maybe 5 years ago and since car done less than 1.5k miles. Would you change it ?

[luke gtr]

All comes down to recommendations and how much you have.

If you have the money, both are a great piece of mind to be done. And I believe most people would tell you to do them.

Any fuel sitting in the oil may have caused degradation.  Personally,  I have reused a timing belt after sitting for 2 years whilst getting a rebuild. Didn't have any issues.

Id probably dump the oil, fill with fresh, and get on your way.

But, keep in mind, I'm just some guy on the internet. 

[GTSBoy]

But don't throw away the unused oil in the opened bottle. That's just daft.

[drifter17a]

If it sits on shelf opened then it is no good and I don’t have a use for it really hence why throw away.