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Date:         Sun, 4 Dec 2011 11:26:31 -0600
Reply-To:     Tom Hargrave <thargrav@HIWAAY.NET>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Tom Hargrave <thargrav@HIWAAY.NET>
Subject:      Re: Oil recommendations simplified
Comments: To: Dennis Haynes <d23haynes57@HOTMAIL.COM>
In-Reply-To:  <BAY152-ds1418FE88BDE90602804156A0B40@phx.gbl>
Content-Type: text/plain; charset="us-ascii"

Dennis,

This is a excellent writ-up, thanks.

One note about silica. Silica = dirt, as in airborne dirt and dust.

Years ago I was running two 1986 Mercedes 300E's about 50,000 / year each and I ran Mobil-1 (15W-50, from memory).

At that time I was using a pre-paid oil analysis service to tell me when to change my oil. I'd change my filter every 5000 miles and pour some of the oil from the filter into the vial & send it in.

Oil analysis is amazing. Not only will it tell you when the oil needs changing by reporting additive and contamination levels, oil analysis will also warn you of a issue you may not even know is happening.

Also, oil analysis let me extend my oil changes to 50,000 miles and I only changed oil then because I felt I needed to.

Anyways, I mailed off samples for both Mercedes one day and the results came back as expected, except for one issue. The reading for both cars showed high levels of silica. I called the company and they explained that high levels of silica almost always means a leak in the air intake that's letting unfiltered air past the air filter.

I knew right away what had changed - I installed K&N air filters and yes they were oiled, they came with oil in little pump spray bottles and I applied the oil as instructed. I pulled the filter out of both cars, installed pleated paper filters, changed the oil and subsequent oil analysis showed that silica readings dropped back to normal. The K&N air filters had only been in the cars a few thousand miles.

I learned a huge lesson with this one. Don't trust after market, no matter how well THEY claim THEIR product performs you have to remember that THEY are motivated to sell THEIR PRODUCT.

This is true for most car additives and "performance enhancers" on the market.

Thanks, Tom Hargrave www.stir-plate.com www.towercooler.com www.kegkits.com

-----Original Message----- From: Vanagon Mailing List [mailto:vanagon@GERRY.VANAGON.COM] On Behalf Of Dennis Haynes Sent: Sunday, December 04, 2011 9:43 AM To: vanagon@GERRY.VANAGON.COM Subject: Oil recommendations simplified

The attached chart is what VW offered for most of their models back in the day. There are two considerations though. As a left over from the air cooled days outside temperature did have an effect on the running oil temperature. In fact overall engine temperature was effected by outside temp. I once drove my 72 bus 400 miles and the oil temp never got over 120F. With the water cooled engines except in extreme conditions the oil is going to at least get as hot as the coolant and then some more depending on speed and load. The other consideration is that the multi-range oils of the day did not maintain viscosity well and often were not even stable. The science then was nowhere as good as it is now.

There are two major requirements for oil viscosity. The most critical to select is at start up. At the lowest temperature expected not only does the oil have to allow the pistons to move at allow the engine to start, it has to flow, be able to splash, and the pressure relief valve has to handle the excess flow. As such the low temp ranges indicated on this chart are still good. You do not want straight 40 oil at low temps due to start up concerns. Things that happen with too heavy an oil at start up include cylinder scuffing and wear, excessive oil pressure resulting blown oil coolers and seals, locked-up spun bearings in the case and I have even seen the oil pump drive tab sheared off. When we get extremely cold weather here on Long Island I see many cars loose the crank and cam seals form them actually getting pushed out from excessive oil pressure since the drains just can't take it when folks start it up and drive without letting some warm up. On the other end of the spectrum the oil has to maintain some minimum viscosity at the highest bulk temperature to maintain film thickness for the bearings, avoid washing past the rings, and maintain sufficient pressure. Here is where the VW boxer engine, (both air and water cooled), need some attention. These engines are really loose tolerance, that gets even worse as the case expands and bearing clearances increase. To make matters worse the pump is a simple design that also gets affected by expansion and there is very little reserve. Then we need to run them close to 4,000 rpm and load them continuously really driving oil temps up. Overfill the crankcase and some other factors and it is possible to see oil temps of 250F or even more. Thankfully we now have multi-weight oils that actually work.

SAE oil viscosity for straight weight oils is specified at 212F. For the multi-weights the lower number is @104F and the upper is still at @212F. This gives little indication of what the oil may actually be at extremes like -10F or 300F. If we look at the product specs for these oils you will see that @212F (where our oil should be),a straight 40 will be thinner than at 15w-15 or 20w-50. So for us this is the better choice at both start up and running for most temperatures. Now note the 15w-40 or 15W-50 is good down to almost 0F. Synthetics with these same ratings can go down even lower as they have very low pour points. So for most of us the 15w-50 is the ideal oil for most conditions. Do note that in extremely cold weather after start let it run for just a minute or so to get some heat in the oil and drive gently and avoid revving the engine more than needed until you see the temp gauge start to move or you feel some heat.

Most engines do not need the high viscosity oils. For the in line VW engines the 5W-40 or 0W-40 oil works just fine. Most modern vehicles now even use 5w-20 or even 0W-20 oils. The vanagon won't like that stuff for long.

As for how often to change oil there are a lot of variables. The only way to know is to do oil analysis. This is best done at the expected half-life of your oil change interval. So VW recommended changing at 7,500 mile intervals for both regular and synthetic? So at ~3,000 miles take a sample and send it in. Be sure to keep the sample clean. The good test programs have pumps and tubes and stuff to help you get a clean sample. Taking one out of the drain pan is not good. The test results will tell if the oil needs to be changed and why. Is it contaminated with dirt, fuel, coolant? Are there excessive wear particles? Are they ferrous or tin/lead/copper, etc.? Is the oil itself actually breaking down? Loss-Gain of viscosity or nitration? You may need to do some interpretation and the lab will help if needed. Yes there is a cost to this but I have saved many engines over the years due to detecting things going wrong before the failure. Coolant and silica are the biggies.

As for synthetics being worth the extra money there is no doubt that conventional oils are getting better and do a really good job. The synthetics though are a premium product and even if the only benefit was using them for longer periods the cost is offset. For our engines the increased temperature range is a real benefit.

Dennis

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