Yes!

In some engines, when used in milder conditions, you can take advantage of the fuel savings and added horsepower of 0-20W oil in accordance with these official Honda-published diagrams available at the following link.

99-03 TL is not mentioned but since the CL is I posted here by association.

http://www.heeltoeauto.com/pitboard/?p=803

You're welcome in advance

 

we have a current thread on this very issue Marcus
thanks for the actual tech info

Yes its totally ok to run 0w20 synthetic in hardcore winter
5-20 to eek out a tiny bit of mileage, or HP you cant feel~
5-30 for best engine protection in above freezing temps--- all those parts rolling and smashing into each other at several thousand times per minute = RPM
the slightly thicker 30 offers more protection

Use a quality oil of your choice and weight with a decent filter, change it when the oil minder light stays on at 7500 miles and the engine should look like new inside at 200kmiles--

 

Well, I made pretty charts and wanted to share them so :P

 

your charts are pretty

 

I run Amsoil 0w-20 and a Amsoil filter in my 03 TL-s on 15k intervals with no issues. No loss of oil and no sludge.