A few of you have requested I post my Used Oil Sample report, but I'm currently away from Winnipeg on business. Fortunately I was able to have Toromont SOS labs in Toronto email the report to me. Overall, the Prius is VERY easy on oil. About the only thing that seemed unusual was an elevated Na (Sodium) level: this could indicate contaminated oil, road salt ingestion (Not applicable this time of the year), a coolant leak, or the use of sodium xylene sulfonate as a motor oil additive. I’m still waiting to hear back from the lab as I sent off a virgin oil sample of Mobil 1 0W-30. If it also has higher Na levels, then there should be no cause for concern. As Toromont SOS labs primarily tests HD and fleet vehicles, they will not expect to see elevated sodium levels in a large diesel motor, as most HD diesel motor oils will not use it. Hence the note of caution when they tested my sample. Typically an elevated Na may indicate a leaking o-ring in a cylinder liner. Here are the details: 2004 Toyota Prius, 24,084km at time of sample, 8,012km on oil. Toyota oil filter and Mobil 1 “SuperSyn†0W-30. An asterisk indicates the out-of-limit reading. Fe 6 Cr 0 Mb 70 Al 2 Cu 1 Pb 0 Sn 0 Si 17 *Na 75* Zn 642 K 3 Ni 0 Ag 0 Fuel residue: 0.0 Glycol residue: 0.0 Moisture residue: 0.0 TBN: 7.5 As you may notice, the “usual†wear metals are very low indeed. I’m sure a lot of this has to do with how Toyota designs motors, as my 2000 GMC Sierra with “Vortec†5.3 always had very high Fe levels. Also note the TBN at slightly over 5,000 miles is still higher than most conventional virgin oils. With the exception of the elevated Na level, the oil may be capable of twice or more the service interval. Once I get the Mobil 1 0W-30 virgin sample, I’ll post it as well. As the glycol test was negative, I’m starting to wonder if Mobil isn’t using C8H9NaO3S to control solubility, as a coupler, or to reduce cold viscosity by a consistent amount. Those are the usual industrial and petrochemical uses of sodium xylene sulfonate. Also, it can be used as a coupler for a detergent.
No secret needed for the cost, please ask as that's a good way to learn. With 7% PST (Provincial Sales Tax) and 7% GST (Federal Goods & Services Tax) it was $20.27 Canadian. It probably isn't necessary to run a used oil analysis every time you change the oil, but it certainly is a good way to see what is going on with your motor. A good example is the mysterious Na level: if it was the middle of winter, driving on dry but salt-encrusted roads, I'd just write it off to salt dust ingestion. At the level involved, this isn't a coolant "leak" but more like a light seepage. As I hinted in my OP, the Na could be from an additive already in the oil. In this case, it could be used as a coupler for an anti-wear additive, as a coupler/carrier for a surfactant (Detergent), to control cold temperature viscosity, many possibilities. Yes, I called Mobil and they claim they can't discuss things like that. You certainly wouldn't notice any change in level in the coolant tank. So in the meantime I'll wait to hear back from Toromont SOS labs about the virgin sample. I'll still probably sample the oil with 4,000km on it, just to satisfy myself.
That's a good tip. Unfortunately, as Mobil 1 is considered "non toxic," they don't have to list ingredients. They are "available upon request" so you know how far I'll get with that: proprietary information. However I did find some surprises: the pour point is only -49 F. I would have thought the pour point would have been much lower for a "0" rated motor oil. At one time Mobil 1 0W-30 used to have a pour of -65 F. The only thing mentioned on the MSDS provided at mobil.com is "This material is not considered to be hazardous according to regulatory guidelines (see MSDS Section 15)." The only chemical mentioned is CAS # 122-39-4 or Diphenylamine (N-Phenylbenzeneamine or C12H11N). If I recall Diphenylamine can be used in a lab setting as titration for detecting things like nitrates (Changes color). It can also be used as an antioxidant, and as a pesticide. Well, that wasn't very helpful, was it?
I hate to say this but call them or a poison control center and tell them your kid drank a half quart of mobile 1 you might well get data.
Jayman - would you consider posting your oil analysis on www.bobistheoilguy.com to get some good feedback from the great people there? These guys really know their stuff and might be able to comment on the Na level.
Over time, I have snagged virgin oil analyses for Mobil 1 synthetic 5W30, and their sodium levels were reported as 5,6, and 7 ppm. Along the lines of an earlier suggestion here, it is likely that a VOA for the Mobil 1 0W30 has been posted at the "Bob is the oil guy" web site.
Oh boy I didn't want to hear that. At the level of Na involved, and the negative report on glycol, it's doubtful Toyota will do anything.
Have you checked at BITOG to see if they have a VOA for your exact oil? In any case, change that oil (if you haven't already) with something that you *know* is low in Na and have the next batch analyzed sort of soon after. If the Na stays high, make a case for Toyota to replace the head gasket. Look at the bright side: whatever is going on, you still don't have any wear metals in the oil.
IF M1 0w-30 is indeed using a Sodium additive in the oil, it is either sodium sulfonate or sodium naphthenesulfonate. The sodium additive has multiple purposes: 1) Detergent 2) Anti-Wear agent 3) Rust Inhibitor 4) Boosts the TBN, as it is also overbased 5) Friction Modifier, which Molybdenum DiSulfide also does. Thus, the sodium additive is used to supplement the low levels of Calcium and Magnesium in these oils, but XOM may also be using Antimony and/or bismuth in this oil, which we are not seeing.
BITOG doesn't have a VOA for this oil, at least the latest formulation. As for the Na being high and having Toyota replace the headgasket, tough luck. Toyota will most likely make an attempt to diagnose the problem by pressure testing, but it will most likely turn out negative unless it is a large leak. Small coolant leaks are VERY difficult to detect and manufacturers are very unwilling to tear an engine apart or start a repair without proof, so you'll need a type of 3rd Party analysis to show that there is actual coolant ingestion; I highly recommend Terry Dyson of Dyson Analysis for Oil Analysis interpretation, he is an excellent and is used by many on BITOG. Small coolant leaks remind me of the GM 3.1/3.4L 6-cyls that will always seep coolant from the intake manifold gasket. When small (which it seems to stay that way), it is impossible to detect by pressure testing, but then again, it was a known issue by GM, so it was often replaced by dealers anyway. However, coolant leakage isn't the problem here, from what I can see.
First, you can have a massive coolant leak and still test negative for glycol. The coolant will react with the hydrocarbons and form an acidic sludge, and will be detected by solids and traces of Na/K in the oil, and sometimes Silicon due to the silicates in the formula. I think the high Na in this case is caused by either contamination, a lab error, or an oil additive (which I'm leaning toward; either from the current oil or from previous oils used). It is also possible that large amounts of Na are ingested by an intake leak, where you are picking up large amounts of road salt. I highly doubt that though, as the upper-end wear isn't affected and the TBN is quite strong. If there was indeed an intake leak, the wear would be much higher not only due the dirt, but the road salts would be quite hard on metals which would raise wear even further, but that isn't occuring here. Next time, use a lab that provides FTIR readings as well as viscosity, which is very important in getting a view on the overall condition of the oil. To those who are concerned about the high Si, it is most likely caused by gasket leaching from a relatively New Toyota.
Thanks for the post over on the WS fluid thread pointing me here,Jay. Very interesting thread. Makes me think about getting my next oil change checked out just for curiousity, . Lots of new info for me to digest, :lol: .
Due to a big crunch at work I forgot to post the follow-up with the virgin oil sample. Sorry about that. All listed in ppm unless noted otherwise: Fe 1 Cr 0 Mo 69 Al 0 Cu 0 Pb 0 Sn 0 Si 1 Na 13 Zn 760 K 3 Ni 0 Ag 0 Glycol, fuel, and moisture residue: all 0.0. TBN 12.2. I've had a lot of contact with the lab personnel and engineers at Caterpillar Toromont, and we've reached the conclusion the Na and Si levels may just be normal for the 2004 Prius motor. They are surprised at the high virigin Na level, you wouldn't want that in a diesel motor. In particular, they asked about the coolant used (BTW It's a non-silicated long-life fluid), and the metalurgy of the motor. Unless something dramatically changes, the motor should last a long time. In particular, the "usual" wear metals are VERY low at change intervals of 8,012km, with plenty of reserve TBN. This motor is easy on oil, at least Mobil 1. In about 2,000km - about a month from now - I'll send off another sample just to verify with Toromont the Prius motor is in good shape.
