Mobil 1 15/50 oil change interval

[P'bert]

I recently bought an '85 300D with a history of Mobil 1 as its engine lubricant, which I have continued. I know that one advantage of synthetic oil is supposed to be extended oil change intervals, but I'd like your collective advice on how long that interval should be. On our Euro 300D, in which I use Delo 400, I change the oil every 3000 miles.

The '85 has about 250,000 miles on its original engine, which is in outstanding condition. How often should I change the Mobil 1 to keep the engine that way?

Phil
'85 300D, California model
'84 Euro 300D, peasant class/manual trans

I don't think Mobil 1 15w50 is diesel rated. I have been leaning to Rotella 5w40 synthetic and Caterpillar Oil (Repackaged Mobil Delvac 1) for my TD with 5000 drain and 2500 filter changes.

[tjohn]

Mobil 1 15W-50 is CF rated, making it appropriate for light use diesel engines (read any passenger car). Furthermore, it and Mobil 1 0W-40 are specifically on Mercedes' schedule of approved motor oils.

You can use extended change intervals with Mobil 1 provided that you get the oil out before the additive package is depleted or the soot levels are too high. You can have oil analysis done to determine what mileage is right for you. I've settled in on 7500 miles, which actually is probably a couple thousand miles early.

[rickjordan]

I know someone who uses Mobil 1 15W-50, every 10K. He drives 30K miles a year in his '91 300D 2.5 He has had oil analysis done and at 10K the soot levels were still within spec. I have switched to this oil for my '87 TD, and may make the switch for my '83. If you extend the intervals, it atually works out to be cheaper than dino at every 3K.

[toknow]

Hi,
I am using Mobil1 Synthetic 15w50, and the engine is very happy with it..
I do not drive the car as daily driver, and I hardly put 4 or 5k /year..
My question, is it OK to extend the interval for one year, if mileage under 5k or so??? should i replace oil filter in between?? what is the max. time after which the oil gets bad even without driving the car??(synthetic oil)

thanks

[rickjordan]

"Toknow", you don't mention what model you have, but your owner's manual may say to change the oil at least once a year if driven less than 5K a year.

I have never used Synthetic oil and religiously change my Oil and Filter every 5,000 km. (about 3,000 miles). My 300DT (190k km.) is strong and no top-up required between oil changes. However, this forum's many threads suggest the use of Synthetic Oil as an improvement, is there really any merit to a switch? Cost more?

BTW, I use Castrol 15W40.

[rickjordan]

The big advantage to synthetic is cold starts, which would definetly apply to you in Canada. I am trying it for the extended drain intervals. Actually I am still on the fence with this dino vs, syn. debate. As they say "proof is in the pudding". I know someone who is the original owner of an '85 Ford T-Bird Turbo Coupe that currently has 190,000 miles on it. He has relgiously done 3K oil changes using Castrol 10W-40. My father owns an '85 300D with 320,000 miles and uses dino oil 10W-40. Neither has had any engine work done. As I mentioned in my previous posting, I am trying it as a time and money saver, using the synthetic.
BTW here in NJ I have only seen 15W-40 by Castrol at one place. The oils I can get just about anywhere is Mobil 1 products and Chevron Delo 400 15W-40 at any Walmart.

There have been many threads on the subject but non conclusive. In an older engines, some say that switching to synthetic prevents oil leaks but others said on the contrary. Hmmm. What’s been your finding?

Anyone had luck with Rotella 5w40 Synthetic? It's sold at wal-mart also, it's about $12 vs. $6 for regular.

[rickjordan]

So far, so good. It has only been a little over 1K miles since I made the switch in my '87 TD. For now, I am keeping my '83 TD on dino oil. With winter coming it will be interesting to see how much faster the '87 starts due to the synthetic oil. On a side note, my owner's manual for my '83 says 15W-40 (dino)is only good down to 23 deg. F., yet the owner's manual for the '87 says it's good for temps as low as 5 deg. F. Now, granted one is a 5cyl. and the other a 6, but I wonder why the disparity.

[Dana B.]

Am running 10K oil and filter changes on Delvac 1. Am switching to Petro Canada Duron 5w-40 syn to save money @$66 a case of four, four-liter jugs.

After searching around and doing some research, it looks like Mobil1 15W-50 is the best option for price, quality, availability, and allround features. After finding Rotella synthetic is just altered dino oil, it's mostly sold as a "I sell synthetic too" product. I'll start off with 6000mile drain and 3000mile filter changes with oil analasis and go from there.

Does this seem reasonable? If I go with WIX insted of Fram filters, should I go with the same drain and filter change times?

Fram filters? I believe you meant Mann filters?