Much less sludge in filter at 102,000 miles - picture

[wwillson]

All,

See my previous post about sludge in my oil filter at 100,000 after 2,000 miles of running Mobil Delvac 1300 15w-40.

http://theoildrop.server101.com/ubb/ultimatebb.php?ubb=get_topic;f=1;t=006340#000000

I changed the oil today at 102,000 and took another picture of the oil filter:

http://ftp.linuxnirvana.com/~wwillson/102000.jpg

It looks like the Delvac has cleaned the engine pretty well - since there is barely any sludge in the filter. Or, at least the Delvac has cleaned out what it can. I can certainly tell that the engine runs smoother, seems to get about 1 MPG better mileage, but can't really tell if it has any more power. I'm tempted to keep running Delvac 15w-40 in the summer and Delvac 1 5w-40 in the winter and start extending the OCI to 4,000.

I'd like your opinion on a couple things.

1) Should I keep running a HDEO like Delvac?

2) Would a treatment of Auto-RX do any good?

3) How much can I safely extend the OCI?

Thanks,

Wayne

 

[SteveS]

Wayne, there's probaly no reason why you shouldn't use an HDEO like the Mobil Delvac 1300 15w-40 you used in your gasoline engine. Most HDEOs have an API gasoline engine qualification as well as their diesel engine qualifications. This is so the same oil can be used in mixed fleets.

There may be a difference between the viscosiity requirements for your vehicle, most HDEOs will be SAE 15W-40 and your vehicle probably has an SAE 5W-30 recommended. Use of the higher viscoity HDEO might lead to HLA noise.

Basically a modern PCMO has a lot of dispersant in its formulation and very little detergent. The dispersant is there to control the build up of soft sludge (though once established, soft sludge can turn hard). There's not a lot detergent in a modern PCMO formulation because gasoline combustion doesn't form hard deposits which require a detergent to remove.

An HDEO contains a lot of detergent, usually based on calcium or magnesium, to remove the harder deposits which are the result of diesel combustion. So an HDEO will clean out existing sludges and other deposits which have already formed in a gsoline engine. Some viscosity index improvers (VIIs) have a tendency to form deposits, and these may be of a form that a dispersant based PCMO may not remove.

In the time before I bought a vehicle for which an SAE 5W-30 was mandatory, I always used an HDEO (Delo 400 Multigrade SAE 15W-40) in my petrol (gasoline) engines and never had any sludge problems even with predominant around city use.

If you're able to continue using an HDEO then there won't be a need to use an engine cleaner. 4000 miles (6000 km) would seem to be an acceptable OCI, but don't push your OCI. Better a small increase in oil costs to achieve a longer engine life - and lower overall lifecycle costs.

[ May 23, 2004, 05:26 PM: Message edited by: SteveS ]

 

[Geoff]

I replaced the main bearings on a Rover v8 at about 100000 miles. Of the 5 main bearings, I can tell you the ones farthest from the oil pump had the most wear in a definate progression, the rear completely worn to copper. To me this implies startup oil pressure is critical. Personally I doubt much if any substantial wear is caused by thin oil at operating temp. I am sure the guys here would recommend the UOA.

Also thinner oils flow faster and have a greater cooling affect on the engine.

If you start your car often each day I would think a thinner oil is better, especially if the oil temp rarely gets very hot.