We finally hit a patch of nice spring weather here in north NJ.
As a result ( I think?) my ML CDI is running like a clock.
Reduced engine clatter, smooth and powerful.
All winter long she has been noisy and a slight bit slow to respond.
Is this due to the 70 deg temps or did I just get a tankful of top quality/ high cetane diesel? Or is it my imagination?

Warmer intake air and a warmer cylinder head will get you a bit better combustion efficiency, less noise, and more power. This is very noticeable on the 61x engines which lack power when first started and get much quieter and pull harder when warmed up. I wouldn't think it would make much difference on a CDI. You may have finally gotten summer diesel, which has a higher energy content than the winter diesel you've been getting for months. In northern Nevada we switch to summer diesel in May.

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Whoever said there's nothing more expensive than a cheap Mercedes never had a cheap Jaguar.

83 300D Turbo with manual conversion, early W126 vented front rotors and H4 headlights 400,xxx miles
08 Suzuki GSX-R600 M4 Slip-on 22,xxx miles
88 Jaguar XJS V12 94,xxx miles. Work in progress.

It's probably the fuel. If the car is running better when warmed up, then there would be no reason for it not to run just as good when at op temp in the winter.

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1991 F250 super-cab 7.3 IDI. (rebuilt by me) Banks Sidewinder turbo, hydroboost brakes, new IP and injectors.
2003 S430 - 107K
1983 300SD - Tanoshii - mostly restored ~400K+.
1983 300SD - Good interior. Engine finally tamed ~250K.
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Good point on the summer blend Skip. Thanks.