Benefits of using higher API rated oils?

[JBT]

Hi guys. I have 2 mid-size diesel SUVs (common rail engines, Asian models) and they specify use of API CF-rated oils. What benefits do I get, if any, by using a higher rated oil (e.g. CI-4) with the same grade?

Another related question. I've been using Mobil Delvac MX (dino) CI-4 rated oil for the last 2 years on these 2 diesel SUVs and I follow OEM OCI. I found 2 sealed bottles of Shell Helix PCMO (API SM/CF rated) in my storage area, left over from my previous Honda CR-V which I already sold about 2 years ago. I was thinking of using this Shell oil in one of the SUVs rather than give it away. You think its fine to use it on the diesels?

 

[Donald]

I think you would benefit from a synthetic oil, but doubt you would gain much by going to a higher grade.

It sounds like your SUVs are spec'ed for the unused containers of Shell, so why not. I myself would use it for make-up oil.

 

[cancov]

Originally Posted By: Donald
I myself would use it for make-up oil.

I thought the same thing when reading JBT's post.

 

[LargeCarManX2]

I believe that the newer rated oils would not be good (in your older engine) as the oil rated for your application.

Also, I would not use a SM oil in your engines....friction modifiers are not good for older diesel engines.

Stay with a CD CF rated oil in your engines....

 

[Shannow]

That's the thing here, it's likely a newer engine, being Common Rail.

As per my previous posts with my Nissan (2003, although the recommendations are on newer ones as well), the Japanese, on even their newer stuff specify an oil no "newer" than CF-4, and will void warranty if CG-4 onwards is used in the engines.

Pushes you into using PCMOs that also meet CF, which surprisingly seems to work.

I was looking forward to using Delvac 1 when I bought a diesel, but instead used M1, Edge 0W-40, Magnatec SP 5W-40 (some good UAOs on it here too).

I'd use the old oil for top-off, and pick an appropriate PCMO also rated CF.

 

[Jim Allen]

Originally Posted By: LargeCarManX2


Also, I would not use a SM oil in your engines....friction modifiers are not good for older diesel engines.



First I've heard this. I presume you mean CJ-4/SM oils and not PCMOs. Could you explain why FMs are bad for older diesels, please.

 

[Shannow]

Used to cause glazing in engines that were run lightly loaded.

(Also did it in improperly run in petrol engines as well).

 

[LargeCarManX2]

Cummins has a statement out about using an oil with friction modifiers and does not want the oil used without expressed manufacture guarantee. Most diesel oils don't use friction modifiers, however, more are starting with the 2007 and up emission rules out. SM and other PCMO's (which was the second question asked, about top off) have friction modifiers in them. Not to say there bad, just making note of what the engine manufactures are saying....Cummins for one.

 

[Shannow]

The american diesels are considered to be very diffferent to the Euro and Japanese.

Nissan expressly don't want the dispersents that are present in the higher API rated oils, claiming that they want the soot to agglomerate and get filtered out, citing camshaft wear as the reason to not want soot dispersed...and particle filters etc. they want low SAPS.

Here's some stuff that I've posted on the different designs, admittedly for larger engines.

 

[m37charlie]

https://cglapps.chevron.com/msdspds/PDSDetailPage.aspx?docDataId=77109&docFormat=PDF

Chevron Delo 300??

Charlie

 

[JBT]

Hi guys. Thanks for the inputs. So this is what I gather from your responses.

1. It is not adviseable to use my left-over petrol engine-rated PCMO (API SM/CF) even though it carries a CF rating since it has friction modifiers that may cause some bad effects in a diesel engine. So I’ll guess I’ll just give it to my brother who has a sedan to use it on.

2. Using a higher API-rated oil (CI-4), which I do now, over the OEM-recommended CF or CF-4 is not as adviseable . I always thought that these newer oils with higher API ratings would be better.

So I’m curious about this now – What makes the CI-4 oil not so good for use on an engine requiring a CF or CF-4 oil? Are there additives present (or absent) in the CI-4 oil that harms the said engine?

 

[m37charlie]

It appears that the very high levels of dispersants in CI4 and CJ4 oils may not be good. These are organic, nonmetallic, and don't show up in an oil analysis - like succinimides.

Charlie

 

[Shannow]

JBT, the SM/CF is pretty much what you are going to be stuck using.


Here's how my ZD30 holds up on 5W-40 Castrol Magnatec SP which has only got CF, and is a group III, with a GrV additive/UMA.
http://www.bobistheoilguy.com/forums/ubb...true#Post588459

Bloke at work just bought a Patrol with the Common Rail version of the engine, and it specifies 5W-30 with the same "no CG-4 or better" recommendation, but now in 5W-30 (which is where I was headed for my next change)

http://www.nulon.com.au/products/Engine_...l/#.T0sxcHmZiuI

It's just a different soot control strategy that the Japanese use...rather than keeping it all dispersed and uniform, they hop that it clumps enough to filter out.