It really depends on what OEM part you want. Some of the "aftermarket " stuff is better than what the factory put on. If you are looking for engine sensors you can use DELPHI brand. They are an OEM supplier. A lot of the parts stores don't carry them or it's special order. Then the price is way higher then if you get on rockauto. Whatever you do stay away from anything BWD, Total junk! According to wikipedia Standard MP makes them. What ever you are looking for do a search for it here, I'm sure you will find a thread about who used what parts and what not to use.

https://en.wikipedia.org/wiki/Standard_Motor_Products

 

I have used Rock Auto in the past but totally forgot about them. I will probably use them going forward although I just used amazon to buy a magnaflow CAT

 

Like others, I Google OEM part numbers... often it comes down to an online MOPAR Parts site.

I've used Amazon for lots of auto parts... free 2 day shipping comes in handy for bulky or heavy parts.

I try to avoid the cheap aftermarket brands where ever possible, and get reputable name brand parts, even if not OEM.
The extra you pay for a name brand part over a cheap part is very quickly offset by the time and money you spend doing the job over.
This is particularly true of sensors...

 

LMC truck. They have a website or you can get a free catalog in the mail. Has just about almost everything

 

Great for body parts/panels

 

What about the water pumps they sell, are they OEM or what brand?

 

OEM I buy from ebay or amazon but I don't need my truck as a DD. I stay away from the chain auto parts stores when I need a part to work. I also like aftermarket parts after I researched them.

 

Don’t know what brand they supply.

I get water pumps from Amazon.
I’ve had good service from Gates brand (noted belt and rubber company).

 

Gates are an amazing company to get water pumps from

 

Sometimes I get in the mood to walk into an actual auto parts store and ask them to get a part for me, usually my friendly rural neighborhood NAPA store but sometimes the O'Reilly store in the same general area.

And then there are some times I am in the mood to order online, usually from Amazon but sometimes some other parts vendors. I wasn't aware that Home Depot and Walmart sold auto parts, generally, except that I did buy a battery from Walmart a while ago.

I probably would not buy auto parts from Home Depot because that is where I usually get my lumber and home improvement stuff and I am in a completely different mindset when I do auto repair and maintenance.

I like different places for different kinds of things... except for Costco, I suppose. I will buy all kinds of things from Costco. Walmart is where I go to buy some groceries and sometimes some clothing like the Wrangler jeans I wear to do all kinds of things.