I bought this 95 E320 Wagon in early June so it was already quite warm in Ohio. It never made any valve or lifter noise. Lately the mornings have been in the low to mid 40's F. On cold start I can hear what I think is a lifter for 3-5 seconds. Should I be concerned?

When I did the first oil changes in June and July I used Mobil One 0W40. Last week I used Mobil One 10W40. The service records show it had been using Kendall GT1 20W50 (car was from Alabama) which seems thick for the temps here.

Could the Mobil One be too thin? Or too thick?

Thanks,

__________________
Tim Benner

00 ML320 170K
95 E320 wgn 160K