20W50 is way too thick.The first number is the thickness of the oil during a cold start.The second number is the thickness when the engine is at operating temperature.You need to use 5W30,10W30,or 10W40 not 20W50.Its too thick at startup and operating temperature.Thicker oil can be used when your bearings are worn and you're trying to increase oil pressure a little but using too thick of a oil causes extra load on internal parts and decreases power because of friction.5W30 is best for winter,5W30 or 10W30 is good for summer,and 10W40 is good if you need a little extra thickness due to worn parts.5W50 can be used by someone who's racing but I don't recommend it for your specific vehicle make and model

If the place does not have the oil your car manual says you should use go somewhere else. The car place just doesn't want you to leave without selling you something. PS---do not go back to that place.

RIGHT ON! I would use MOBIL ONE 0W-20 oil which reduced friction and gets MORE fuel mileage. All things change over time when it comes to cars and engines. Try PENNZOIL ULTRA 5W-30 and do NOT use the ceiling oils found in many quicko oil change centers! Lots of cars cared this way end up in JUNK YARDS. BAD oil makes TAR and sludge that bake into metals and cause extra internal heat In this modern age, SYNTHETICS save on gas, make more power and lower emissions while saving converters and exhaust systems!

Absolutely not! Over 80% of all engine wear happens during cold starts. The thicker the oil the slower the oil pump forces lubricant to frictional surfaces.

What's wrong with the manufacturers recommendation which is 5W-20? They know more about the motor in your car than a Nit Wit at a box store.

Never give them your business again! If they don't have 10-30 and are a professional shop, that is a bad sign. Recommending the wrong oil (what they have in stock) instead and possibly damaging/ruining your engine, down right unacceptable. I would have walked out and never returned. Probably would let everyone I know about it as well so nobody else goes there.

20W50 would simply be too heavy and thick for your Mazda, regardless of mileage. Stick with 10W30 for the life of the automobile.

The condition of over 100,000 miles on an engine is not relevant. This "guy" at the lube center is ill trained and offers bad information. Use the recommend oil grade in the owner's manual. If the engine is not using oil and not leaking oil, there is no need to change the oil being used. Engines these days have higher quality materials in the rings and seals and other components. Worn or damaged engines that use oil or leak oil is a different story. The leaks need to be repaired by a mechanic. The worn engine that "evaporates" oil also need to be repaired. If this engine is OK, there is no need to do anything.

I drive the car to work and school, not reving the car too much, just normal driving.

mileage: 126K miles

2005 Mazda 3, with 2.0L engine, and Auto transmision.

The guy at the lube center nearby told me I can use 20x50 since has over 100K miles..

The 10x30 motor is more expensive, and they dont have it. I was planning on using 10x30

Will there be any problems internally if I use 20x50 being a thicker oil?

Thanks!