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MG TD TF 1500 - Oil level after engine rebuild


Hello everyone,

I would like to share an observation regarding my MG TD with XPAG engine and would be interested in the experiences of other TD/XPAG owners.

After sitting idle for a long period, the engine underwent an extensive rebuild: new pistons, connecting rods, head gasket, camshaft, tappets, rocker arms/shaft, bearings, timing chain and sprockets, front and rear oil seals, and an oil pump overhaul.

Upon return, the oil level on the dipstick was not in the “Full” range but around the “EmptyHalf” range. The break-in oil had presumably already been changed. This starting point was documented, and the oil level was subsequently topped up to the operating level. I therefore do not count this initial top-up as oil consumption.

After the first few drives, a relatively significant drop in oil level became apparent. After just 280 km (approx. 174 miles), 0.8 liters (approx. 0.85 US quarts) had to be added. This corresponds to an oil consumption rate of approx. 2.9 liters per 1,000 km — about 1 US quart per 200 miles. Following this top-up and another approx. 120 km (75 miles) of driving, the oil consumption, or drop in level, appears to have slowed down significantly.

Engine speed did not exceed 3,000 rpm during the break-in phase. The engine runs smoothly, and oil pressure and temperature readings are normal. No blue smoke is visible from the exhaust. Externally, there are minor traces of oil after parking, but no loss of oil on a scale that would explain the initial drop in level. Fresh oil was observed at the breather pipe.

I am particularly interested in the experiences of other XPAG drivers:

Is it known or plausible for a freshly rebuilt XPAG to initially “expel” oil, perhaps via the breather, or for the oil level to settle down after an initial period of fluctuation?

Do your engines tend to settle at a specific oil level, effectively stabilizing there even if initially filled up to the “Full” mark?

What specific areas would you check before going into a more in-depth diagnosis: spark plug condition, breather system, underbody/oil misting, compression test, or leak-down test?

I am explicitly not looking to assign blame, but rather seeking a technical perspective based on practical experience with the XPAG engine. The rebuilder, an MG specialist, finds this level of oil consumption hard to believe. Does the collective wisdom of this forum offer any deeper insights into this matter?

Best regards,

W_Mueller
W_Mueller

You don’t mention anything about valves, valve guides, or valve stem oil sealing rings (in the collets).
R WILSON

Well, older style cars often use some oil when new piston rings are installed until the rings fully bed in, which typically takes 500 to 1,500 miles. During this break-in period, minor oil consumption is normal as the new metal surfaces wear together to create a tight seal against the cylinder walls.
Christopher Couper

Sorry - all valve Equipment is also nee
W_Mueller

A couple of questions come to mind. Have you had someone follow you to observe the tailpipe on acceleration, deceleration and cruising? A lot of time acceleration right after deceleration will blow out a goodly puff of blue smoke if oil is being sucked in around the valve stems.

Was anything special done to the crankcase ventilation system? Stock air cleaner or aftermarket? If the valve cover vent is not open, pressure can build up pushing oil out the road draft pipe. Also, the pushrod cover gasket can block the access to the road draft pipe causing excess pressure in the crankcase.

Lastly, the dipstick tube may have been installed differently causing you to inadvertently overfill with oil.

Just some thoughts.

Jud


J K Chapin

HI W,

You are not very clear on how long Running in Oil was in the car, or what oil you are using now, so I may be wrong.

Running in oil should be used for between 500mls (800km) and a 1000miles of driving with various speeds and loads. Do not let the engine lug down or rev to high. It is unlikely your garage did this, so I would put Running in Oil back in and do it again.

After you feel the engine is run in and not using any oil, change to a high zinc 20W-50 mineral oil. Do not use modern synthetic or semi synthetic oils, if you really feel you have rot use them wait until you have done 10,000miles so everything is bedded in nicely, but you may still eat your camshaft.

Good luck Bernie
B W Wood

Thanks Christopher and Jud

these are very useful points and exactly the kind of practical XPAG experience I was hoping for.

I should add an update after another drive. After a further approx. 220 km / 137 miles, I measured a drop of about 6 mm on the dipstick marking. The marked range on my dipstick is about 20 mm, so this is a much smaller drop than I initially observed. This seems to support Christopher's point that oil consumption may be higher during the early running-in period and then begin to settle down. This is encouraging, but I do not want to draw conclusions too early.

I certainly hope the consumption continues to decrease and eventually reaches a reasonable level.

Regarding the dipstick: I had already looked into the issue of incorrect XPAG dipsticks some years ago, because I know there are different versions. Since I do not know every detail of what may have been removed or refitted during the rebuild, I checked this again. All relevant dimensions correspond to the factory specification. I will attach the factory document and an extract from an older forum post dealing with this issue.

On the crankcase/valve gear ventilation: the hose between the valve cover and the air cleaner/carburettor area was missing when the car was returned. Because the two connections have different diameters, I made up a stepped hose arrangement using two oil/fuel-resistant hoses pushed into each other. Following information from older forum posts, I also included a restrictor disc with an orifice of about 2–3 mm in that hose. So the valve cover ventilation is not completely open, but restricted in the way described in those older discussions.

Before the next oil change, I plan to top up once more and then measure the actual drop over the following known mileage under the same conditions. That should give a better picture of whether the oil level is continuing to stabilize.

Your comments on the crankcase ventilation are also very helpful. The breather/ventilation arrangement is now high on my list of things to check, along with the spark plugs and any oil misting under the car.

Best regards,
Winfried





W_Mueller

I think it would be worth testing all four cylinders for compression - you never know what might be shown up!
Regarding the MGCC service information sheet 86, I’m surprised that it does not actually mention the dipstick part number 24407.
R WILSON

Yes that's the partnumber on my dipstick - exactly "24407 ENGINE". I guess it is not mentioned because it refers only to the engine dipstick guide tubes.
W_Mueller

OK, it looks like we have the correct dipstick so I guess I need to change my cartoon to read "Do you sell shorter dipstick guide tubes?"

Jud

J K Chapin

Hi Bernie,

thank you, that is helpful too.

There is one specific point in my case which I should perhaps mention. The camshaft and tappets are not completely new. They had already run together for about 500 km before the engine had to be taken apart again because of another issue.

So my understanding is that the very critical first cam/tappet break-in phase had already taken place. Of course the piston rings and bores may still need further bedding-in after the rebuild, and I fully agree about varying speed and load, avoiding lugging and avoiding high rpm.

The rebuilder used running-in oil only for the initial running-in process and then changed it. From a previous rebuilt classic engine I remember similar advice: use running-in oil only for a short initial period and change it early. In that case the running-in oil was red in colour and the advice was to change it after about 50 km.

For that reason I am hesitant to put running-in oil back in now without a specific technical reason, especially as the oil level drop seems to be decreasing.

So for the moment I am inclined to continue careful running-in on a suitable mineral classic oil, monitor the oil level closely, and change the oil at the next planned interval.
W_Mueller

This thread was discussed between 02/08/2026 and 03/08/2026

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