Upgrade RAM more than the maximum capacity?

Max is 8gb on these.

 

I think the OP was right, that the max was 4gb, but going above that would slow performance.

EFI update then takes you to 8GB max as reported in this blogpost:
http://blog.macsales.com/9102-secret-firmware-lets-late-08-macbooks-use-8gb

 

Your MacBook supports up to 8GB of RAM. Specs are here.

You can find specs on all Apple products, including maximum RAM:

• By visiting EveryMac.com: Actual Maximum RAM
• By selecting your model on the Crucial Memory Advisor™ Tool to find RAM information
• By using Mactracker
• By entering your serial number here to find specs for your model. (Be aware that some models can use more RAM than Apple shows. Check EveryMac to verify actual usable RAM.)

 

You can use any brand of RAM. RAM of the same specs will have the same performance, regardless of brand.

 

I have the same Macbook! late 2008. Mine has the 2.4 core two duo. About a year ago I bought this 8 GB memory kit for $38.00

http://www.newegg.com/Product/Product.aspx?Item=N82E16820148276

But now it's not available and it seems the prices on 8GB DDR3 1066 have gone up :/

But it's been working very well and I love the extra performance! I am running OSX Mavericks on this thing and it's really fast. I just bought this SSD from Newegg which was also on sale. So if you want a SSD then you should see all the deals that are posted on this site called slick deals.net and get a SSD on sale!