how can one tell 100% that the oil was changed

[paoester]

Originally Posted by dogememe
The uv dye will stay in. Some oil is left between oil changes so the new oil will become dyed immediately.
About 10% of old oil is left in the sump normally, true. The UV dye will be cut down 90%. I'd think that would be glowing dimly at best, on the dipstick test UV flashlight test.

 

[kschachn]

It glows pretty strongly even after several oil changes. I think the amount of dye they have you add is way more than is necessary, I did this on a friend's car once and every time I changed oil for him you could see the stuff that drained out of the filter pretty clearly.

 

[paoester]

Maybe if one puts in only a little UV dye, like 25% full instruction's dose, then did a dark-garage dipstick flashlight test after driving only 20 miles on it, to compare to what it looks like after a real oil change.
This is too much trouble.

 

[Hall]

Originally Posted by WhyMe
ok thanks guy. i am going to change it for her just to be sure.

What does she think about this all ? Now she has (unfounded) reasons to no longer trust this dealer when in fact they may have changed the oil.

 

[GoldDot40]

One could also apply this to the drain plug...then check it after the oil change. If they go to the trouble of breaking the seal to loosen the plug, you can likely bet they drained it.

 

[dogememe]

Originally Posted by kschachn
It glows pretty strongly even after several oil changes. I think the amount of dye they have you add is way more than is necessary, I did this on a friend's car once and every time I changed oil for him you could see the stuff that drained out of the filter pretty clearly.

Yeah I put a dose of uv dye in the power steering system in my 95 Chevy then changed the steering gearbox each time, and each time I flushed the system. Well, that truck is still in the family and the power steering fluid is still bright!!

 

[paoester]

Originally Posted by GoldDot40
One could also apply this to the drain plug...then check it after the oil change. If they go to the trouble of breaking the seal to loosen the plug, you can likely bet they drained it.

That or the Torque Paste mentioned above in another post, would not pass the I'm-in-a-hurry oil change technican scam where they just drain off some and replace a couple of quarts, then they might keep the new quarts to take home to their own stash.
Originally Posted by Triple_Se7en
The vehicle returned to me had dark oil - not clear. Appears as if the bolt was removed - a new washer inserted and then screwed back on. Looks like I received three new quarts of oil, instead of five..


I do agree that, if the drain plug is taken off, probably ALL the oil got out.

I'm curious about the UV dye persistence issue discussed above. I might try the 25% reduced dosage method, and check the dipstick before and after an oil change to see if I can tell a difference !!

 

[The motor guy]

Look at the oil pan right where the drain plug is. Is it dusty/dirty? If so they didn't change the oil. Is there oil hanging from the drain plug, but the oil pan is still dusty/dirty? They changed it, but didn't bother to wipe the plug off. Does the bottom of the oil pan look clean like it was freshly wiped with oil around the drain plug? If so, they changed the oil and did it properly.

Also, if you pay attention to what kind of oil filter you run on your vehicle, then typically they will put a different brand on and the filter will like nice and new/clean on the outside. If you're a real nut like me, then you can take a sharpie and mark the oil filter in some way and also take a paint marker to the drain pan.

 

[JunkdrawerDog]

If the drain plug is cross threaded, the filter leaking cos it's only finger tight and the level a quart over full, then yeah, they changed it, lol!

 

[SatinSilver]

Originally Posted by WhyMe
ok thanks guy. i am going to change it for her just to be sure. one thing about dealer oil change is that you never see the car. they wisk it away and come back later. at least at the quick change places one can see them work most of the time.


Many of the 2012+ Toyotas have 10k oil change schedules with synthetic oil. However the service sticker they apply to the windshield and mileage counter designate a 5k service. The 5k, 15k, 25k, etc. services consist of tire rotation, check fluid levels, misc. inspections, etc. No oil change is included with this service and it runs $35 or so here. Check her invoice and see if an oil filter and oil are listed on it. This may help to avoid some confusion going forward. Plus the dealer may not have done anything wrong.

 

[Yah-Tah-Hey]

100% certainty= you did it yourself and you are not mentally ill.