Hello, I am about to purchase in a few weeks a used 99' Audi A6 with 79,000mi.

What are the questions I need to ask or the things to be cautious of? Any heads up?

Also I've had a little confusion on what type of oil the car is to take.. 5w30 or 0w-40?

 

The big things consider / check for before buying an Audi:

Timing belt/water pump/thermostat
Valve cover gaskets
Tires
Brakes

And the overall service history of the car. If service is pretty much non-existent it may make me think twice about buying the car. If the records are pretty good, then you know the owner was somewhat aware of what was going on with their car.

As far as oil, I'm running full synthetic Mobile 1 0w-40 in my 2.7T.

 

Wow, only 79k?? That's crazy. Mine is just about to go past 200k. Definitely make sure the timing belt has been done or you'll be looking at $1500 just for that (which depending for what you're getting the car for, might be fine). You're right around the milage mark for when it should be done (some push it to 100k+, but you have to also take in effect the age of the car).

Don't ignore the transmission. While it's low enough miles where you are probably okay, make sure that it isn't doing anything that feels weird (jolting into gear, taking a while to shift, etc).

Other things to check (added to the list Neb gave above): control arms, general electronics (see if most things are working properly).

If the car is clean and runs well and has a good service record you'll probably get a lot out of it! For that low of mileage you should probably be paying around 4k-4.5k (less if the timing belt has not been done).

 

great find! same as above. if no records, definitely have timing belt, pulleys and water pump replaced as age could have affected the belt. same with serpentine belt. i have a 99 with 212,000. i flush the tranny and filter every 50,000. make sure all recalls have been done especially the headlight harness, mine caught fire. fuel filter should be replace and mass air flow sensor cleaned. look under car for any fluid leaks. valve cover gaskets and cam seals are known to leak. i fixed this around 100k and haven't had an issue since. it also good practice to replace cam seals during timing belt change. also, check PVC hose. it's plastic and becomes brittle over time. oil- 5w 30 synthetic for non turbo. if your are a DIYer then you will enjoy this car. maintenance is key. you should easily get 100k+ out of it.

 

Awesome, thank you a lot. I will make sure I have all of those done. Is there a recommendation on the best brand to use for timing belt? Quality difference or different type of material? I am willing to invest a little more in this vehicle to make sure that it is running okay for a long time.

 

i have been buying my TB kit from Blauparts- see link below- Never had an issue- others may chime in just my opinion.

Website:
Audi Parts - Vw Parts - Audi Parts Vw Parts Kit Company - Blauparts

 

Another good place for parts is Genuine & OEM European Car Parts | BMW Volvo Audi VW Mercedes Saab

They have decent prices of stuff and are pretty reasonable when it comes to support and customer service.