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I recently took my car into what is supposed to be the best garage in town (certainly, the most expensive). Foolishly, partly because of their reputation, I didn't take precautions I'd normally take like taking a photo of the oil state before going in, I just knew it was a slightly brownish amber colour and might need changing. I didn't question them when they said one of the things they'd do was change the oil and filter and fix a few related issues with the oil pan.

After getting the car back, it looks like they didn't actually do several of the jobs they were supposed to, and there are plenty of other reasons to be suspicious (for example, we agreed a quote including changing the brake pads, but they didn't change them, and it wasn't until after I'd come to pick up the car, after they'd told me everything was done, and after I pointed out to them that the brake pads were the same as when I took the car in, that they admitted or explained this and prepared a new invoice with the cost of the brake pads removed...).

I'm starting to wonder if they might have lied about changing the oil as well. This is a country with very low standards for mechanics, so it wouldn't be particularly surprising.

How can I tell if the oil has indeed been recently changed?

One thing I've tried already is to look at the oil using the dipstick, and it looks very similar to how I remember it being before taking the car in. Looking at various guides, to my eye it looks like it's somewhere between "fresh" and "should be changed". This car is petrol, not diesel where the oil often changes colour immediately after an oil change, but it is quite old ('97 Toyota RAV4) if that's relevant. I'm not sure if this is evidence it's old oil that was getting close to needing changing but didn't need it urgently, or if it could be new oil that simply discoloured a little naturally.

Here's a photo of how the oil is currently (I really wish I'd taken one like this before going in...), taken using the dipstick while the engine is cold. If the work was done, it was last Friday, and this photo was taken on the Tuesday morning after driving for about an hour to take the car home on the Monday.

enter image description here

Update - I've questioned the guy from the garage about this (and the other problems). He's insisting that any discoloration is because it's an old car, and he's (rather shamelessly) taking the opportunity to try to upsell me an oil flush... I'm starting to suspect that they did a very half-arsed oil change, just draining and replacing whatever came out of the sump quickly, possibly not even warming it first...

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  • Hmm... I'm afraid that doesn't look like fresh oil to me. I'd say they probably didn't change it, but let's see what the community says. :)
    – anonymous2
    Mar 28, 2017 at 12:37
  • You could look at the state of the oil filter (Dust, dirt etc. on the outside)
    – Martin
    Mar 28, 2017 at 12:47
  • @Myself that's a good idea. In theory they could just wipe the oil filter clean so it looked new, but if they didn't even bother to do that, it'd be good evidence!
    – user56reinstatemonica8
    Mar 28, 2017 at 12:49
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    Used oil usually turns black. That oil on the napkin is not black. It looks new to me.
    – cory
    Mar 28, 2017 at 15:32
  • The oil on the dipstick is never going to be completely clean after an oil change. Besides the inside of the engine still being wet with the old oil, there are also plenty of passageways where it can't be drained from. That's why all manufacturers will specify different oil capacities for an oil change vs. a brand new, never used engine.
    – atraudes
    Mar 28, 2017 at 23:41

2 Answers 2

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The best way is to smell it.

Oil that has been used will always have a smell of gas because of piston blow-by.

Piston rings have gaps to accommodate for thermal expansion, so there is always a bit of combustion gases going to the crank case and the oil will pick up the smell; unless you have a car with a dry sump but this is very uncommon.

Smell it and you will know right away if the oil is new or not.

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  • It's a dead giveaway, but that's not necessarily always the case. I know the smell you're referring to because I was dealing with a leaky injector for a while, but all of the other oil changes I've done haven't had this smell.
    – atraudes
    Mar 28, 2017 at 23:37
  • it will depend on the usage of the oil, but if you do 10k miles with oil, it will always have some gasoline in it; the assumption I made is that the oil change was requested at an interval when it was due; the oil then will have at least 10k miles on it.
    – Thomas
    Mar 29, 2017 at 0:13
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It might be fine... used diesel oil is normally black as you say. How many miles did you have since the previous oil change?

There is no way of being sure.

The "post oil change colour" depends on how much oil they actually drained out, for example, I jack my car up on one side and leave it overnight which gets a little bit more old oil out.

If I do a quick oil change, where I only wait until the draining oil slows to a drip, then the colour of the oil after the first drive is considerably darker than waiting overnight.

I doubt any garage will leave a car taking up space when they can just wait for the draining oil to slow to a drip. Many places don't even remove the drain plug, they insert a thin vacuum hose into the drain plug and suck the oil out, so there is a lot of discrepancy.

Also, you could pose as a new customer, and ask what brand of oil filter they normally use for a diesel Toyota RAV4, and check if that is what's fitted to yours and if it is clean and shiny. Do you remember what was fitted during the last oil change? In case they wiped it clean.

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  • It's a petrol car, not a diesel - says so in the title, I'll edit the question body so it's clearer
    – user56reinstatemonica8
    Mar 28, 2017 at 13:23

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