Mads

Hi

I'm going to put my 89 S4 away until spring. but do i have to change the oil before ?
last oilchange was about 4000 km ago, in april 2006.
Am i a bad father if i dont change the oil ?

Regards

Mads

Vilhuer

If you are going to chance it in spring anyway, its better to do it now.

Doug Hillary

Hi Mads,
Roskilde - a lovely place - I once lived in Taastrup (Ludvig Hegners Alle off Roskildevej), then in Roarsvej in Fredericksberg - I worked for VW and then Caltex-Chevron in Adelgade near Nyhavn during 1960s

I would change the oil now and do at least 500kms on the new oil before storage - use a good quality oil

Regards

Mads

Hi

Dough, thats like 10 km from where i live sometimes the world is smaller than you think

It was my plan to change the oil next spring, i don't have time to do 500 km before storage, i have to put it away this weekend, becaus my insurance is not valid from 15 november to 15 march. but a least i can do 50 km

Mads

Marine Blue

Mads

As I understand it, if you're running synthetic it should have enough PH Balance conditioners to prevent the oil from becoming acidic. If you're running regular oil it wouldn't hurt to change it before the winter just to be safe. Doug Hillary has some great info about this, might be worth doing a search.

Mads

the oil is syntetich 5/40W SL/CF.

Mads

Doug Hillary

Hi Mads,
I agree with Afshin, that oil you are using will have sufficient anti-corrosion additives to last until Denmark's lovely Spring arrives

Regards

JTM

Doug,

I've read your comments here for many years and ALWAYS look forward to your opinion. Thanks for your continued participation! I'm curious about the recommendation to drive >500km following an oil change prior to storage period. Is it simply to take advantage of circulation of the fresh oil's lubrication and cleaning properties? Or is it something more specific, perhaps activation or release of a Vapor Phase Inhibitor (VPI), or other additives, that you've mentioned in prior threads? Are VPIs found in all oils or just in the highly regarded HDEOs, that might make HDEOs the oil of choice for storage applications? Thanks in advance for your reply. JTM

Mads

thats good to hear i didn't change the oil last saturday
I will change in april.

Mads

Doug Hillary

Hi,
JTM - you obviously have an interest and some real knowledge of lubricants. That's great, sharing is what these Forums is about

1 - After a normal oil change the oil will always go through a cleaning and replating phase. This is a chemically "reactive" period and nothing much to do with "lubrication". This will be a short period if the oil is being replaced by the same Brand and formulation - longer if not. Generally 500km is a reasonable compromise although it could be much longer if using a different oil Brand or formulation

2 - A Vapour Phase Inhibitor is (VPI) not present in all HDEOs. Those that contain it are a great "all year round" lubricant for low use engines and are mainly targeted at the Agricultural and Industrial market.
It works to passivate metal surfaces etc. not covered by the lubricant
The oil needs to be a "mixed fleet" HDEO with a viscosity of 15w-40 when used in a Porsche engine - this will ensure that the oil is more than robust enough at high temperatures and for annual oil changes

3 - And yes, such an HDEO is an ideal choice for a 928 if the car is parked up for the winter

Note: The "pitting" which is often seen on cam faces in low use engines (and confused with wear) is primarily caused by using an unsuitable lubricant, infrequent oil changes and/or by the metallurgy used. This is not picked up by Used Oil Analysis. An oil containing a VPI will assist in preventing this type of thing

I hope this is of interest

Regards

JTM

Doug,

Thanks for your informative reply. Does your specific reference to 15W-40 dino HDEOs indicate that the 5W-40 synthetic HDEOs, including Delvac and Rotella, lack VPI? In general, if synthetic HDEOs do contain VPI, is it more likely to be found in Group IV-V vs Group III synthetics. I've never seen mention of VPI on a oil spec sheet, is there a way to identify those oils with VPI? Sorry for all of the questions, just tryng to be able to identify those oils with VPI for low mileage, air-cooled, 911 application. I'm currently a 5W-40 Rotella user.

Best Regards.

Doug Hillary

Hi,
JTM - Normally the spec sheet will include a reference to the VPI if it is included

Normally a synthetic mixed fleet HDEO 5w-40 lubricant will not have a VPI unless application specific (for instance a version of Delvac 1 Branded for and sold by CAT may)

These lubricants are really at the top end of the "food chain" and in the case of Rotella T Synthetic 5w-40 it has a high TBN (11.5). This indicates that it will survive up to two years in a petrol engine which is in good shape. This oil is also Volvo VDS 2 (perhaps 3 too) and MB228.5 Approved which is a good indication of its durability. This version of Rotella uses a highly advanced Group 3 base as I recall

The same can be said of Delvac 1 5w-40 but this lubricant is a more complex Group 4/5 product that contains around 22% complex ester content - it has a TBN of 11. Hence its higher price!

IMHO you are already using one of the very best lubricants available for your 911.

Sadly Rotella T Synthetic 5w-40 is not sold in Australia

Regards

JTM

Thanks Much Doug.