I have a 2007 Mazda 3S with the 2.3 liter engine and 5-speed manual. I just turned over 60,100 miles. For the past 36,000 miles I have had my oil changed at AutoTire in Chesterfield, MO every 6,000 miles using Valvoline DuroBlend.

Yesterday I decided to change my own oil and switch to pure synthetic. You can imagine my surprise when I unscrewed the cap from my oil filter housing and found NO filter. It was empty. I've driven for at least 6,000 miles with no filter. It could be longer since I don't know when it last had one.

What damage could have been done to my engine? What's the remedy? Is an oil flush a good idea? Please help. I'm shocked.

 

First of all, beat the sh*t out of the guys @ AutoTire in Chesterfield, MO, then move out of state.
I would at least give them a call (or stop by) and tell them what you found out. I doubt they would be that desperate for a few extra $$$ that they would short you the filter on purpose... of course I have been surprised by the extent of greed before too so maybe I'm not the best person to ask?

They SHOULD recommend a service that, imo, they SHOULD do for you for free!
Short of that, yes, I would say a full oil flush is the least you can do.
Then switch over(convert) to the 2.0L filter, which is a spin-on. If they forget that you will know right away, and so will they.

Extent of damage is liable to be nil, assuming you drive your car in a normal, civilized fashion and don't auto-x, time trial, or track it in any way.

 

In many ways oil filters are overrated. Gasp! How dare I say such a thing?

The truth is that many-many engines were built for decades without oil filters, and many of them are still operating this very day. Case in point, the old Cessna that I did my basic flight training in featured a 300 cubic inch "boxer-six" engine with a simple mesh screen to "filter" out just the big chuncks. In reality the screen was there to tell the maintenance folks that the engine was coming undone as that was the only time anything would ever be trapped. The engine in that plane was nearly 30 years old, ran like a top, and had over 2,200 hours on it (even though it had a recommended overhaul time of 1,700-1,800 hours). Funny thing though, when the owner finally did drop in a new motor, it came with a filter.

 

Yes, but remember please that these old cars, and probably the old plane you are speaking of too, had to be maintained much more often than a modern vehicle does. The oil quality wasn't as good, no detergents to help clean in that oil, machining not as exact, and they probably did oil changes every 300-600 miles vs. 5-10,000 we do today.

 

Believe it or not, they used detergent oil beyond the first 100 hours or so and they only did oil changes every 50 hours, easily in excess of 5,000 miles.