I hope this doesn't seem too ridiculous, but when do you check the oil? When the engine is cold or when its warm?

I dont leak much oil so I dont get too finnicky worrying about it changing levels quick after an oil change, but I do check it regularly before startup, when its cold. Is that proper?

Thanka you like so much oh my gah

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A junkyard is not for junk

its a OM617A benzo 5 banga DT

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A junkyard is not for junk

Hot or cold it won't show up on the stick if it isn't in the pan. As long as the oil has been given time to return to the oil pan the reading will be accurate.

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84 300SD
85 380SE
83 528e
95 318ic

Good practice is once a week ,I ck the trannie once every month to see if small leaks have risen .The most important part of keeping the diesel engine happy,oil level. A better header for youe thread would be "How often do you check your oil? unless your not sure how to read the stick ,2 marks at bottom ,the lower mark is in safe level ,upper mark is topped off ,from bottom to top mark is in range ,no oil on stick is very bad.If not kept in the oil range your next thread might read"Why does my engine sound like its trying to jump out of the engine bay/"
Read the engine oil with engine off ,read it cold or hot.
For the trannie fluid you want it hot but not a complete necessary practice. The fluid check on the trans though will require the car running at time of inspecting its fluid level.

It's always nice to have the car on a level surface.

I've always heard hot oil will give an exaggerated, positive amount on the dipstick

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1998 Ford Escort ZX2 5 speed - 279,000 miles My Daily

1992 Mercedes 300D 2.5 202,000 - Pure junk
2000 Mercedes E320 Black - 136,000 miles - Needs repair

Don't forget to grease the screw and threads on the spring compressor.

What he said.

Cold is good, because you know it’s all in the pan. I’ve always heard (and I think it’s even in the manual?) that checking it hot is fine, as long as you give it about 10 minutes after shut down to let most of the oil drain back down to the pan.

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A few things to think about.

There is a range of oil level that will give acceptable operation, it isn't that critical. If you check hot or immediately after shut down, if the level is mid way up, you are fine. If at the min or below, add 1/2 of the volume between min / max then check cold or after sitting when you get a chance.

When a car goes up / down hills or around a curve, the oil sloshes so your perfect level is now not so perfect.

Most engines will run on 2 QT in the pan, however long term it is better to have more oil so it has a chance to deaerate / not slosh away from the pickup.

Very good point, I was surprised to see no baffles in the pan when I had the one off on my engine as it was out and on the stand. That's the same one I had a bugger of a time getting the new seal to actually seal.

My practice has always been to check the oil in the garage first thing in the morning once a week if it's a daily driver, the floor is about as flat as I have found, even though technically it has a slight fall to allow water to drain out the front door incase you ever wanted to hose it out (most do) mine has an 1/16" fall per foot, so around 2" for the entire length of the garage.

On a long trip, I'll check it at every fill up, just fill, to inside and pay or pee, and by then it's settled enough to check.

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1983 W123 300TD US spec Turbo engine, with Euro bumpers and manual climate control, and manual transmission.

I generally check mine once a month and I always do it cold. When the oil warms up, it gets thinner and it's harder to read the level on the stick.

It's also a good idea to wipe the stick off on your first withdrawal, then reinsert and withdraw again to check the level. The SDL tends to give inconsistent readings on the dipstick (lousy design), so I generally read the level 3 times to get an average. The SL and the Honda only need to be read once, they'll always give the same level on the stick.

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Current stable:
1995 E320 149K (Nancy)
1983 500SL 120K (SLoL)

Black Sheep:
1985 524TD 167K (TotalDumpster™)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

Measure cold, drive for 15 minutes, then measure warm, the two readings will be very different. This is why hot vs cold is vehicle and manufacturer dependent. Some recommend stone cold, some recommend operating temperature. Check your owners manual, as the marks on the dipstick are calibrated to that. Oil expands as it warms, so it matters what the manufacturer specifies here. I think all the German manufacturers specify an engine fully warmed up and at operating temperature. I know for a fact VW does, Audi does, and Porsche does. In fact, the late model Porsches have an electronic dipstick that won't let you take a reading unless the engine is warmed to full operating temperature. What does Mercedes recommend?

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1998 E300 turbodiesel

America's Rights and Freedoms Are Not The Enemy!

WIS instructs two minutes after shutting off a warm engine.

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Paul

Never on my car or the wife’s minivan. On the 240D its checked at every time the tank is filled so its on a level surface. Sometimes it meeds a quart about 2,800 sometimes none between changes.

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1981 240D Four on the floor, Orient Red over Parchment, bought with 154,000 but it's a daily driver and up to 180,000 miles, mostly original paint and all original interior.

This.

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'80 300SD - '83 240D - '00 E55 AMG - '02 G500

U guys literally DID NOT answer his question....(besides one person) Just went on and on about yourselves. (The one problem that often arises on all forums it seems) he didnt ask when u guys chexk ur oil. He asked when to check it his, not how often but specifically when.

U can chexk it hot or cold but the engine has to be off. If u chexk it hot, like right after u turn your car off, u need to wait 5 or even better 10 mins. That way all the oil falls back dowb to the pan. If the engine has sat long enoigh to be cold that means all the oil has seeped back down to the pan for sure so thats always your best bet.

Dont chexk it when engine is running because most of the oil will be up in your engine and not in the pan

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Take a pill, man. Forums are a source of ANECDOTAL advice. That means personal experiences mixed in with repair manual procedures and tips/tricks passed down from older mechanics and people with greasy hands.

It's assumed that nobody is going to check the oil with the engine running. If they did, they'd quickly learn why you don't. Especially on an old diesel.

The FSM procedure was posted above. As said by myself and alluded to by a couple of other posters, that isn't always easy to do. The SDL in particular has a polished dipstick with no crosshatching. Once the engine is hot, the oil leaves a very thin film on it that is nearly impossible to read. While reading it cold isn't "by the book" it does allow an accurate reading of what's sitting in the sump without resorting to using a microscope.

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Current stable:
1995 E320 149K (Nancy)
1983 500SL 120K (SLoL)

Black Sheep:
1985 524TD 167K (TotalDumpster™)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)