Does a 2010 camry LE require synthetic oil ?

Question edited for clarity.

Changing the serpentine belt has no bearing on it.

Did you completely remove the Throttle body and clean both sides of carbon? Often, people only clean the side they can see.

Check out the Camry Throttle Body relearn video.

https://www.google.com/search?q=2010+Toyota+Camry+LE%2C+throttle+body+relearn

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every 5000 miles or 6 months.

depends on oil
if 0w-20 synthetic oil is required this pushes the service to 10,000 miles and 12 months whichever comes first
unless you are such as: driving off-road, on dirt roads, towing a trailer,
http://toyota.custhelp.com/app/answers/detail/a_id/7604/~/what-are-the-oil-change-intervals-using-synthetic-oil%3F

crank shaft sensor , get the code cleared and see if it comes back , if does then more invetigations will be required , are there any running problems ?

As your windows usually are slim jim resistant so its more prudent to get locksmith to open and could make new set of lost keys using vin number, make, model, year.

Yes, certain 2010 Toyota Camrys were involved in both the sticking accelerator pedal and the floormat recalls.
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New Arrivals
Emergency power supply

ALL Vehicles have the same oil change requirement

You drive 20,000 miles a year div x 5 =every 4,000 miles

You drive 16,500 miles a year div x 4= every 4,125 miles

You drive 12,000 miles a year div x 3=every 4,000 miles

So every 10,13 or 17 weeks

3,4 or 5 times a year you change your oil

Some repair shops will tell you its 100,000 mile oil or it never needs changing.il tell you what,i change trany oil every 30,000 miles,unless its synthetic, then every 60,000 miles,i own a toyota and work on many, i change it every 30,000 mile. what i mean is i flush it,i do a bg service flush,with a cleaner and conditioner,and the filter i change every 90,000 miles.

Go to Google and enter "youtube toyota camry oil change." This is a fairly good video on how to address the oil change procedure that should be similar to your (and my) 2010 Camry LE, 2.5L; not exact, but you'll get the idea. Also, Google "Avalon oil change pdf" and click on the '05/'06 Avalon item to get a printable version that should also give help/hints for your 2010 2.5L. Now all we have to do is get permission from Toyota to waive the requirement for "only" 0W20 synthetic ($$$) in favor of either less expensive and more readily available 5W20 or 0W30 and extend the change interval from a very low 5000 miles to something more reasonable like 7500 miles or, better still, 10K! I've written to them to see what kind of answer they'll give, but am not hopeful of relief on that front. By the way, Lisle says their filter removal tool Pt. No. 54930 is the correct one and should be available from O'Reilly's Auto Parts; if not on shelf, should be orderable. Good Luck.

The filter is under the engine. It is not a traditional "spin-on" oil filter. The filter is now a "cartridge-type", and is in an aluminum housing.

the recommened oil is any major brand 10W-30W