l know that for standard oil, l need to change it every 5,000 miles. If l were use 5W-20, how often should l change the oil?

You should actually change it every 3000 miles or every 3 months no matter what kind of oil you use.

the 3,000 mile oil changes are no longer needed. What you are doing is excellent.

Scion recommends u change the oil in ur engine every 5000 miles. You mentioned standard oil & then u asked about 5w20. 5 w20 is an oil weight not a specific type of oil. The weight of the oil does not determine how fast it wears out (breaks down). Although, the lighter oil (5w20 compared to 5w30 - which is the recommended weight) will work, it does not cover the overall needs of ur engine.
l believe the question u r trying to ask is comparing conventional oil to synthetic oils (or blends). Synthetic oils r better, because they r specifically engineered to be. But it is not the oil as much as the additive package that breaks down. Dirt suspended in the oil & severe temperature ranges as well as other contaminates (normal) - all due to everyday driving, cause these additives to break down. Your driving habits & the environment u drive in determine how often u should change the oil, not the weight or type of oil, so much. l use synthetic oil in my tC, & still find it good practice to change my oil every 4000 miles as opposed to the 5000 Scion recommends. Brand is about marketing and/or personal preference. Use the weight that is recommended (5w30 in this case), & decide between conventional oil & synthetics - cost & benefits, because both will work & keep regular maintenance on all ur systems, not just the motor oil. Toyotas r the easiest vehicles to maintain (except the 4Runners grrrr.). Hope this info is helpful.

The owners manual specifies every 5,000 miles or 6 months, whichever comes first. A lot of research time and money is spent by the manufacturer to decide what is the appropriate weight and frequency. l would go with what they say.

Of course there are still people that change every 3,000 miles. That certainly is not going to hurt anything.

Every car is different. It should be every 3000 miles or 3 months, but some cars can last a little longer.
All types of oil last the same distance & time.
5w-20 lasts just as long as 5w-30, which lasts just as long as 10w-30.
You Scion should use 5w-30 & or 5w-20.
10w-30 recommended in cold weather.
Mixing oils also does not effect the way an engine performs & will not damage the engine.
Even High Mileage & synthetics last just as long as regular oil.
Your car manual should say the time recommended for the oil changes. Which should be around 3000 miles or 3 months. Whichever comes first. A way to check if u need an oil change is to check the oil dipstick & wipe the oil with a white napkin. If the oil is dark brown or black, then u need an oil chnage. If it is light brown or gold, then it is not ready for an oil change.

Ok for all Scion tC is the recommended change is 5 months or 5,000 miles(not 3 mos 3,000 miles). Now depending on what year ur tC is depends on what oil it takes (your oil cap will give u the answer). All 07 & up tC is take 5W20 or 0W20(for cold weather). And if it was produced before then it takes 5W30 for all conditions.

Im assuming u have a 5W30 tC & r asking would it change if u switched to a lighter oil. No it would not but u should really always stick with the manufacturer oil recommendations.


Hope this Helps

l agree with savage however pick a oil and stay with it DO NOT SWITCH BETWEEN CONVENTIONAL OILS TO SYNTHETICS AND BACK TO CONVENTIONAL ESPECIALLY with a car that has high mileage or you will develope leaks