A self change is about 20 dollars. I've been getting my oil at wal-mart and usually several gallons at at time. This is mostly because each of the last 4 visits, the priced jumped 3 dollars. I also keep an eye on sales at local parts shops, as they have specials you can get 5 qts and filter for 23/25.00...I personally service around 10k or when the oil turns black. This has served me well, as my 78 still runs good at 500k. I do not recommend using any oil that's cheap. Stick to one oil brand...and I don't endorse Pennzoil..........my choice is quaker state...in 10-40 and not the hi-mileage. Castrol is good too. Mobil and Royal purple are higher end oils and you'll pay for it too...in my opinion....needlessly. Takes about 20 min. and you can save half the cost over a quick lube...plus have the added benefit of greasing and looking for other potential problems...