Oil cap left off - damage?

[Lord E38]

Some idiot (me) left the oil cap off this morning before going to the petrol station. As I pulled back into the drive I noticed smoke coming from the engine. I opened the bonnet and guess what... oil all over the head and the bonnet insulation.

I have a 2 hour drive this evening - will it be okay just with a wipe down? The level never went below the minimum and the cap was off for 25 minutes at the most. I wasn't driving like a madman (too bloody hot)

Car is a buggered old Volvo.

[Pebbles167]

In my experience it'll be fine. I've done the same.

Someone may have something more scientific to add, but as long as the level is okay I wouldn't worry.

[DaveCWK]

I'm sure it will be fine

[LennyM1984]

Lord E38 said:

Some idiot (me) left the oil cap off this morning before going to the petrol station. As I pulled back into the drive I noticed smoke coming from the engine. I opened the bonnet and guess what... oil all over the head and the bonnet insulation.

I have a 2 hour drive this evening - will it be okay just with a wipe down? The level never went below the minimum and the cap was off for 25 minutes at the most. I wasn't driving like a madman (too bloody hot)

Car is a buggered old Volvo.

I did a 20 minute race with the oil cap missing from my car (the smoke only became apparent as we were doing the parade lap at the end). It took me bloody ages to clean up all the oil (air flow had spread it everywhere from the engine all the way back to the diffuser). That was 2 years ago and the car has done many races since without issue.

(If it helps explaining the mess to wife/friends, I claimed that the oil cap had been blown off by excess pressure in the engine! Reality was, I had been topping it up in the paddock and had clearly forgotten to put it back on)

[sanguinary]

You'll have to ignore the oil burning smell for the next few miles though!

[renmure]

I also did the same without any dire consequences. Had the engine steam cleaned locally which came up fab and it almost felt like a win.

[NotDan]

Driving to mongolia, we met a group of 8 pulled over at the side of the ‘road’ somewhere in the Kazakh desert with the bonnet up and oil cap missing from their Prius.

We topped them up, cable tied a silicon glove over the top and sent them on their way - you’ll be fine (if a little smelly for a few miles)!

[spikeyhead]

It's probably fine, but check the air filter

[SystemOfAFrown]

It'll be perfectly fine if the oil level didn't drop below min, just a massive PITA to clean up. Had to do this quite recently after not quite correctly fitting the oil cap on my Smart Roadster, I removed the worst of it with brake cleaner and then used copious amount of Muc-Off (I had a 5L bottle) with a paint brush and then a regular low pressure hose from the tap to wash it off.

I have quite a few old washing up bowls I used for oil changes and parts washing etc. so put them all under the engine to catch as much of the run-off as I could.

[TwinKam]

Back in the mid eighties, I set fire to a Mk1 Astra by precisely this method. Those that know the SOHC Vauxhall engine of the time will be aware that it was possible to inspect the first two cam lobes when topping up the oil... there was no baffle. Without a filler cap in place, oil is launched in a graceful arc onto the forward-mounted exhaust manifold. Any that hits the underside for the bonnet instead, has a free drop courtesy of Mr Gravity to the same hot place. Alerted by the smell, I stopped and opened the bonnet. The sudden inrush of oxygen was all that was needed to complete the holy trinity of required elements for a conflagration. Thankfully, dropping the bonnet shut snuffed it out just as quickly. No lasting harm, but a right filthy mess to clear up... and a lesson learned.

[Smint]

Won't do any lasting harm, if anything it might help keep a few odd bolts from corroding worse than otherwise, most of will have done that in our time.

As above worth the time cleaning up, especially washing down anything rubber ie hoses and engine mountings, not sure where the spark plugs hide but maybe worth checking oil hasn't filled the spark plug recesses, syringe might be the tool for removing excess from those.

[catso]

Smint said:

not sure where the spark plugs hide but maybe worth checking oil hasn't filled the spark plug recesses, syringe might be the tool for removing excess from those.

This is worth checking, my Son had a Renault Clio which had a tendency for the RH side scuttle drain to block with leaves etc. and due to the positioning/design of the engine, this meant that any rainwater overflow would run into the end spark plug recess, causing it to misfire - quite a regular occurrence actually.

Given that the oil filler cap was also right next to that plug, any overflow from that may well have done the same thing?

As for the original question, as the oil didn't run low I highly doubt any damage was done, other than the mess to clean up.

[Leveret]

Engines, especially old bog standard ones, are pretty resilient to neglect. Even if the oil level was well below the minimum mark, perhaps even temporarily just at the bottom of the dipstick, they will survive unscathed. I'm sure many mechanics will have encountered such negligence with no lasting ill effects. Even I have (not one of my families cars!) observed this on occasion.

But these didn't last long on full throttle and no coolant......

https://www.youtube.com/shorts/Lr1caBHC2OU

.......but this did!

https://www.youtube.com/watch?v=pcYBgod7L_k

[the tribester]

I've done it.

The engine was fine, but the bonnet insulation lost its body and sagged all around the edge.