New 172 do they use a lot of oil

[ray d]

Hi all, I have got a new 55 and I have hat to top it up with oil. The first time I toped it up I thought it had been missed in the garage. Cant remember how much I put into it (possibly 1/2 a litre). that was at 500 miles. Checked today again and needed to put in about 1/4 litre now 580 miles. Can anyone reassure me it is normal. Don't see any smoke out the pipes and there are no leaks. I had a 171 before this one and I never had to top it up at all between services.

 

[Trickythemerc]

I would be very concerned if it used 1/4 litre in 80 miles. Get it to the dealer ASAP

 

[grober]

Measuring oil levels is tricky and must be made at the same engine oil temperature with the car on level ground each time for a valid comparison. Because the oil expands with temperature its difficult to compare readings. Many Mercs have something like 2 litres of oil volume between the fill and full levels on the engine dipstick so 0.5 / 0.25 litres is not that much bearing in mind the accuracy of measurement. Many advocate running a cold engine oil level at approx 2/3--3/4 between the fill and full marks routinely to allow for a bit of expansion when hot. I don't like engines that are filled to the brim/ full level when cold as its often difficult to see exactly what the oil level is and there is a danger of overfilling- this can cause problems with air entrainment and subsequent oil loss. Try for a cold oil level that's just discernable BELOW the full level and monitor it closely for a few weeks to see what's happening. Don't be tempted to top things up unless the level gets perilously close to the fill level mark and see how things go.

 

[190]

I never run to the full mark on any vehicle as generally the more airspace there is above the oil the easier it is for the engine breather and that can reduce oil consumption. Running lower may be a concern on an engine that's an oil burner unless it's routinely monitored but for the purpose of checking oil consumption I'd run it at the halfway mark.

 

[brucemillar]

Grober, gives the perfect answer. Follow that you will know if you have an issue. I suspect that you do not. You are simply seeing the differences in tolerance on the dip stick, temperature allowance, car level etc.

 

[AMG19]

The 55 engine I have been assured by my indy does burn oil. I've heard 1/2 litre every 1000 miles is not uncommon when the car is still reasonably new. Apparently oil consumption will reduce with time as the engine wears in.
1/4 litre every 80 miles however is very excessive. Grober has given some good advice to make sure that your figures are accurate.

 

[st13phil]

Measuring oil levels is tricky and must be made at the same engine oil temperature with the car on level ground each time for a valid comparison.

^ This.

You should measure the oil level after getting the engine to normal operating temperature (oil that is, not just water temperature), then switching off and allowing 5 minutes for the oil to drain back to the sump and settle. This should be done on level ground, or if slightly off-level at least make sure the car is parked in the same place when you make the measurements.

As Graeme said, 0.5 / 0.25 litres is not that much bearing in mind the accuracy of measurement, especially if the engine was at different temperatures or the car was parked in different places when the measurements were taken.

As a general rule, AMG V8's do tend to use a bit of oil (my Biturbo consumes a litre in around 4k miles), and a new engine will often consume oil faster in the first few thousand miles until the rings bed in. Even if your measurements are absolutely correct, 0.75 litres in 580 miles would not be considered excessive oil consumption.

 

[ray d]

Hi guys, thanks for the replies and it puts my mind at ease a bit. I will keep a better measurement of the oil and I will measure the oil at the same condition every time. I was in TVR's for about 10 years and the last V8 chimera would have used about a litre every 1K miles which was classed as normal. Never thought about rings etc having to bed in but I now remember the general chat was drive them hard for the first 1K miles and that will bed them in well but the Mrs is having nothing of that because she read the sticker in the window "not over 4500rpm"