what, beside an oil & filter change do you recommend i do to my 03 mustang with 28,000 miles?
Keep your tires properly inflated, use the right motor oil, inspect all hoses and belts, check your battery, get it inspected by a good mechanic (if you can still find one).
Open up the glove compartment, take out the booklet containing the manufacturer’s maintenance schedule, and make sure that all specified maintenance procedures up to at least 28k are performed before your trip. Even better would be performing all of the maintenance procedures that are specified for up to 32k or 33k.
Have the maintenance taken care of at least a few days prior to leaving, just in case something like an oil leak or a disconnected vacuum hose is discovered after the service. And, whatever you do, DO NOT have your car’s maintenance taken care of at a quick lube place.
What was posted already plus: ALWAYS open the hood and recheck the engine oil level as well as ALL other fluids (after servicing has been done) YOURSELF before you leave the premises.
Make sure to wipe the oil dipstick clean first. I seen people lift the dipstick out but not clean it off to read it. NOT wise.
The service guide that came with your owner manual probably has several things scheduled at 30 K including transmission service for auto transmissions.
I firmly believe that transmission fluid should be changed every 30k miles and you should check all fluids, tire pressure, along with a couple of extras that may not be recommended.
Those 2 extras are the fuel filter and air filter. Fuel filters should be changed about every 15-20k miles or even more often if a fuel contamination problem is suspected. A car may run fine with a partially clogged filter but this is rough on the fuel pump. Filters are much cheaper than pump assemblies is the way I look at it; just like trans fluid changes are far cheaper than new transmissions.
At 28k miles the air filter is probably also due for replacement even if appears fine visually.
Depending on the environment, sometimes even 10k miles is too long between air filter changes.