Oil viscosity question

[htbetz]

I get a couple drips of oil a night under my rebuilt 2.7L. It's been a brutally hot summer in the northeast here and was wondering if switching to 20/50 oil would help. I'm currently using 10/40.
From the posts it seems that oil leaks are the norm rather than the exception on these engines.

[Chuck Moreland]

I doubt it will solve your leaks, but I'd recommend going to 20/50 in hot weather anyway.

[Wayne 962]

Chase the leaks down first - and see where they are coming from...

-Wayne

[KTL]

Regardless of oil leaks, you might want to consider switching to 20W50 for this reason alone:

Taken from Pelican tech. article (I recall reading this information elsewhere)

http://www.pelicanparts.com/techarticles/mult_gas_and_oil/mult_oil_article.htm

"Very few manufacturers recommend 10W-40 any more, and some threaten to void warranties if it is used. It was not included in this article for that reason. 20W-50 is the same 30 point spread, but because it starts with a heavier base it requires less viscosity index improvers (polymers) to do the job. AMSOIL can formulate their 10W-30 and 15W-40 with no viscosity index improvers but uses some in the 10W-40 and 5W-30. Mobil 1 uses no viscosity improvers in their 5W-30, and I assume the new 10W-30. Follow your manufacturer's recommendations as to which weights are appropriate for your vehicle"

But, oil tech. changes and Porsche has revised their recommendations for their vehicles in the recent past. The information below is stuff I recall reading in Panorama, and I copied it from their website's tech info. section.

Just a little over a month ago on 11-30-01, Porsche issued a new oil bulletin that is significantly changed. The latest list of approved synthetic motor oils from Porsche includes Mobil 1 0W-40, Mobil 1 5W-40, Valvoline High Performance Synthetic, 5W-30, and there is also a Castrol/Syntec 5W-50 listed. As before, Porsche says the oils can be used for all 4, 6, and 8 cylinder Porsche engines from 1973 on. The Mobil 1 0W-40 now comes in all the new Porsches, including the Turbos, but some owners have had a problem finding it in retail outlets. The biggest change in this latest data is that temperature charts lowered the upper limit on the 0W-30 synthetic oils that were previously 40C (104F) to 30C (86F). These newest Porsche temperature charts do not show a synthetic 10W-30, but do show 10W-40s and 5W-40s going to a higher (but undefined) temperature limit than the 0W-30 synthetic oils which have the revised lower maximum limit of 86F ambient temperature. We will keep trying to learn more about these changes and pass them on, but in the meantime, I guess I would feel better about a 5W-40 or higher oil for running under warm ambient temperatures.

Allan Caldwell Website 1-09-02

The first article we published on Porsche approved synthethic oils was in the October, 2000, Panorama ("Porsche Approved Engine Oils") which covered the approved temperature ranges for various viscosities and also listed a number of approved U.S. engine oils. In 2001, there were Porsche tech bulletins released in June that revised downward the upper temperature limits on some of the synthetics and so we included the revised temperature data in a second Panorama article in August of 2001, ("Engine Maintenance--The On-Going Evolution"). The bottom line of the updated temperature data is that in order to use a synthetic oil at outside air temperatures greater than 85F, the higher viscosity number in the two-number rating should be 40 or above. The previous data had indicated synthetics with a 0W-30, 5W-30 or 10W-30 would go to 100F ambient temperatures, whereas the later data says they are limited to 85F. The August, 2001, Panorama article did not list any specific brands but the referenced June, 2001, Tech Bulletins list the following approved oils:

Castrol/Syntec 5W-50 Mobil 1 0W-40, 5W-40 Sun Oil/Sunoco Synturo Gold 5W-40 Texaco/Havoline Formula 3 Synthetic 5W-40 Valvoline/High Performance Synthetic 5W-30

Viscosities recommended for the Turbo are 0W-40, 5W-40 and 5W-50. Allan Caldwell - PCA WebSite - 8/9/2002

We reviewed Porsche's oil recommendations in two Panorama articles, "Porsche Approved Oils," 10/00, and "Engine Maintenance--The On-Going Evolution," 08/01. Porsche originally approved use of synthetic oils in 1980, and every new Porsche since August, 1992, has been shipped with synthetic oil. Porsche currently installs 0W-40 in all the new cars and recommends it for old cars back to 1973. Note, however, that they also approve a number of conventional oils with more limited temperature ranges. I doubt that your 911 will burn any less synthetic oil, but in some cases, as in my own car, a 911SC, there was less usage because the synthetics have fewer additives to burn off. Allan Caldwell - PCA WebSite - 8/20/2002


There you go. For whatever it's worth (peace of mind I guess?)..............

[Superman]

I haven't decided whether to use synthetic oil, now that my engine is rebuilt. Perhaps. That stuff protects better, particularly in extreme heat situations (240 F and above). But I live in the Great Northwest where ambient air temperatures are pretty cool. Our entire annual temperature swing might be only fifty-five degrees (30-85 F between the coolest January morning to the hottest August afternoon) On at least 250 days of the year, the temperature is in the fifties at some point. 911s LOVE it here.

I use 20/50 in either Valvoline Racing or Kendall GT, all year. I would not consider a 40-wt oil in a hotter climate. MHO.

[Jdub]

Super is right. The Northwest is a great place to pick up your next Pcar. Ambient temp easy on the car, no salted roads, just pure fresh rain, interiors and paint NOT shot from sun, and ex dot.coms up the proverbial wazzu with cars they can no longer afford.

In fact, there will be a HUGE auctioning of cars from the collection of a local bookcookin' felon that includes a Pcar among others. Murphy auctioneers if you are interested, in Kenmore, Washington.

John