I don't think that 85degC (or thereabouts) is an issue - the specifications for the i5-2410M shows Tjunction (should that be TjunctionMax?) as 100degC.
Assuming it is TjunctionMax - the point at which your laptop would automatically shutdown - then you are some way off this. It is true that when electronics get hotter their lifespan decreases, but CPUs will get hotter with use (due to the laws of physics basically) and are designed with this in mind...
For what it is worth, I have seen my partners HP laptop (an AMD chip) running at similar temperatures with no problems (her laptop is now 3 1/2 years old), and whilst I haven't checked my laptop recently (HP Pavilion dv9000 series) it certainly has run similarly hot at times, and is now almost 5 years old.
As a side note, I would recommend you keep the vents clear of dust and free from obstruction - good airflow is key to keeping electronics cool!
Hope this helps reassure you.
thanks scott glad to hear that but after I post that I play civilization 5 and I see my temp reach 93 C and the game runs quite lagged.
do you think it's my RAM or my processor?
another question is can I clean my fan notebook fan with a vacuum cleaner or should I clean it by a tissue or something else by opening the fan case?
I'm not sure about modern games and i3/i5/i7 issues, although certainly there are a lot of posts about it on the web in general. However, the minimum requirements for Civ V include 2GB RAM; with the i5 (as in your machine), some of your 2GB will be taken for the integrated graphics so technically you don't meet this requirement. Integrated graphics and gaming rarely go together well (in my experience), although Intel are certainly active in releasing updates for gaming-related issues, so perhaps an updated driver would help? Just a thought, but worth checking out.
As before, you are running hot but (just) within the CPU specifications, although it sounds like the game isn't playable. Have you considered reducing the game settings to the lowest mode to reduce the load on the graphics processing?
As for cleaning fans, you need to be very careful using a vacuum/compressed air - spinning the fan up to a too high a speed can damage or shorten the life of the fan bearings. You can use a vacuum or compressed air if you can insert something between the fan blades to stop it spinning (a small screwdriver, for example). Obviously this would need to be done with the machine off, any battery removed, and with great care. My prefered method is a strip-down and rebuild but this is a timely endeavour!
EDIT: I didn't quite answer all of your question there! I think that adding some more RAM couldn't hurt - it is usually the cheapest and most rewarding upgrade a PC can have. Of course, that is more money... My preference has always been to max out the motherboard (my new HTPC has 16GB RAM - complete overkill I admit, but only slightly more expensive than 8GB and nothing in the overall cost). As for the CPU, the i5 exceeds the minimum specification listed by Firaxis, but as before I am not sure about modern gaming and i3/i5/i7 gaming issues.
I know about the requirements and I also already think about upgrading my RAM to 4gb, I already reduced the graphics to very low state and it still lagged and I only play it around 20 minutes and my processor heat reach maximum 90 C.
hmm maybe its better if I take my laptop to someone pro in cleaning it because it seems quite complicated..