Don't fret much over the oil pressure fluctuations. Oil pressure changes depending on any number of variables:

1. Heat - the oil pressure drops as the oil heats up.
2. Engine speed - the oil pressure drops at idle.
3. Age - the oil pressure drops as the oil ages.

Unless you're using synthetic oil in the engine, I vote for using anything between a 10W-30 and 20W-50 weight during the heat of summer. I wouldn't fret too much over the weight of the oil, as long as it's reasonable. You're correct with your logic on how to interpret the two oil weight numbers.

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95 E320 Cabriolet, 169K

I don't know of any MB engine that uses 10w-30 or 5w-30. Most euro motors seem to like a thicker oil. Well unless it is extremly cold.

How cold does it get in Georgia? It can't be that cold I wouldn't worry about cold starts. Heck my diesel cranks over with 15w-50 in the crankcase when it is 20 out. She doesn't crank any slower the oil pressure jsut takes a little longer to come up.

ocap not to be a pain but you really should do a search. This topic and your engine have come up many times. You will get better answers.

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2016 Corvette Stingray 2LT
1969 280SE
2023 Ram 1500
2007 Tiara 3200

Thanks for your reply. I'm thinking of Mobil 1 0W40... is this appropriate? - i don't really care about cost savings and i've heard mobil 1 is the best engine oil. I know another poster mentioned it above, but i'm really wary of sticking in an oill with a 0 in it... LOL

You will have a hard time finding a better oil than Mobil 1 0w-40. If the 0 bothers you Mobil makes 5w-40 Delvac 1 but it is hard to find and if you have to order it will cost more.

My friend's dad is using 0w-40 in his 95 S600 and it runs great. The oil pressure is fine.

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2016 Corvette Stingray 2LT
1969 280SE
2023 Ram 1500
2007 Tiara 3200

Thx a ton... Sorry about being lazy to search the board, but I'd probably wind up still being unsure about it, so i'd rather have someone go "buy this oil"

Ok buy 0w-40. Pepboys was just running a sale on it $3.99 a quart. Walmart also usually has great prices.

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2016 Corvette Stingray 2LT
1969 280SE
2023 Ram 1500
2007 Tiara 3200

thx... i'm looking at sams club, they sell mobil1 but not in the 0w40... crap

If you're going with synthetic, then these lower weights should be fine. Mobil 1 is a great oil. I too am leery of using 0 weights... just not used to it, even though I live in a cold climate! But I do tend to shy away from oils that have too wide of a weight range. They are purported to have a higher tendency to form engine deposits.

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95 E320 Cabriolet, 169K