Switching from synthetic to regualr??
 

Alright so I have a question about my 911 3.2. Ever since I've had the car, I would change the oil with synthetic oil. Now one of my friends who is a Porsche mechanic told me to use regular oil. So i used straight 40 conventional oil.

Now I know its bad to change from different types of oil. Was that a bad move or a good one? Should i stay with the regular oil or should I go back to synthetic and stay with it?

I need help with this one. Also the motor has 30k on it.

I also what weight oil should I use or is straight 40 ok?

Thanks.

It is OK to switch between syn and natural oil. I suggest, as would many others, to use Brad Penn 20-50. You might do a search for the "ultimate oil thread" and read up a bit.

I have read the same over and over, so +1

The previous owner used synthetic for years. No leaks.
Since I got it, I have used sythetic (Mobile1); no leaks and almost no burn. Really tiny.

Thinking about going to Brad Penn 20-50, but have heard issues with some people switching to it when there was no obvious issue.

Milt, would you still recommend the swap to BP?

thanks...

Proper Lithium levels in Oil
 

I have a 3.0L in a '76 and a 2.4L in a 914-6 conversion. I have read several articles recently warning us about using modern oils in older cars. Shell rotella has been recommended as a non-synthetic oil with the appropriate levels for older cams with flat followers. I believe all oils for diesel engines CD-J rated or better (Rotella is one) have the appropriate makeup. I plan to use the same oil in my 911 engines in the future as I use in the diesel engine in my sailboat, in my case usually Delo-400. Anybody see any problems?

Mel

If you choose a diesel oil, make sure its API-CI rated product. The newest ones are mostly all CJ and there are better things to use in a 911, now.

You may even want to look at 15W40 - often dropping a grade won't hurt and it may actually give you slightly better milage!

So was my move to regular straight 40 a good one?

It's fine. unless it gets really old where you live. I use 40 wt. Rotella, in fact, I am changing ot the oil tomorrow.

Straight weight is not good for a street car that will see a range of temperatures. On start up, here in sunny California, with 20W50 oil, I can see the effect of viscosity on oil pressure. If I rev it to 3000 or so, I get 60+ psi. If I was not careful, I could easily get 100 psi. This is not good for rubber seals and causes oil leaks.

You really should use a multi-viscosity formula, just not to wide a range or it will have too much parafin. 20W50 for most places, 10W40 for colder.

Besides, Brad Penn and Swepco are known to be great base stocks that hold up well in high-performance engines. This is in addition to the Zinc and Posphorous.

I bought a case of 20W50 Brad Penn from Charles Navarro of LN Engineering (author of oil thread). He is in Momence, Illinois, and I am in Thousand Oaks, California.

It amounted to less than $7 per quart and was reasonable to me for much better oil than I can get at my local FLAPS.

:)

I disagree. In SoCal, a straight weight oil is fine year round. Even for a street car. Single wts. are also used to fix small oil leaks, as it does not get thin like multi wts.

Edit: Engine has over 230,000 on it with no top end. Yes it's had its share of leaks, but age had more to do with that.

I agree that straight weights have their place, just like racing oils without detergents.

I do not know if the OP lives in a climate like Southern California.

I prefer to go easy on start up even with the multi-viscosity here in So Cal. I do not pre-warm the car or go through a priming checklist like a race car owner might do so the high oil pressures make me anxious until the temps come up. The car leaks a good deal, including a baffling slick around the oil filter after driving for a while and the usual case line, rear main seal, heat exchanger area leaks that make so much smoke.

I want all the protection I can.

I move that we make all further comments about general oil dynamics and performance in the ultimate oil thread: http://forums.pelicanparts.com/porsche-911-technical-forum/367300-ultimate-motor-oil-thread-why-we-hate-cj4-sm-oils-52.html

I know you asked Milt, but IMO if you have no issues (leaks) using Mobile1, I personally would continue using it. I tried it several years ago, and began to get a few drops on my garage floor so I switched back to dino (Kendall GT1 - the new formula). I've recently been using Brad Penn (the original Kendall GT1 - the green stuff from the same oil well) that's partially synthetic with no issues, so I'm happy. Can't beat the protection of a full synthetic like Mobil1, and it's more readily available (although I can get BP locally at a decent price). If it ain't broke...

The latest info from Mobil states that their Mobil 1 Extended Performance 15W50 is for engines w/ flat tappets, like ours.

Fl - since your move request was apparently denied...

can you explain your paraffin comment above?

I've always heard the issue with a wide temperature range for a multiviscosity oil was the addition VI improvers required. These long chain "springy" molecules break down relatively easily, forming... "scum"

For all of you Mobil 1 fans, here's a blurb from Mobil 1's "Extended Performance Page"
Features and Benefits

Mobil 1 Extended Performance 5W-20, 5W-30, 10W-30 and 15W-50 are made with a proprietary blend of high performance synthetic basestocks fortified with an advanced additive system, designed especially to deliver performance and protection during longer service intervals. Mobil 1 Extended Performance oils are uniquely designed to provide outstanding levels of performance, cleaning power and engine protection, even during longer oil change intervals. Mobil 1 Extended Performance oils are available in a wide range of viscosities. The 5W-20 and 5W-30 viscosities are recommended viscosity grades for newer vehicles. The 10W-30 viscosity provides excellent all-season performance and protection. Mobil 1 Extended Performance 15W-50 is formulated to provide outstanding engine protection for high performance engines and for consumers who want a higher viscosity oil and higher anti-wear performance ( ZDDP) than typically required by modern vehicles.

Heres another blurb on their new lower viscosity "Racing Oil" with higher levels of Zinc and Phosphorus.I've been using Mobil 1 15W-50 in my race car. How are these new oils better/different?

Mobil 1 15W-50 is a higher viscosity oil that delivers a thick oil film for protection of high performance engines. While Mobil 1 15W-50 can be used and is recommended for both street and track use, the new Mobil 1 Racing oils are only recommended for use in race engines at the track. Mobil 1 Racing 0W-30 and 0W-20 are lower viscosity oils designed to increase power output versus higher viscosity oils. Most importantly, Mobil 1 Racing oils are formulated with anti-wear (Zinc/Phosphorus) chemistries at twice the level of automotive street oils to protect race engines including high loaded flat tappet designs used in the NASCAR series

I am under the impression that Viscosity Index (VI) improvers are based on parafin molecules, the springy ones that make the oil behave like 20W at low temperatures and 50W at high temperatures.

Perhaps I am mistaken or remember incorrectly. I need to ask Charles.

Anyway, (I think) the parafin molecules used to stretch the viscosity index break down easier at high temperatures and shear than straight 50W of the same good base stock oil.

Straight 50W Brad Penn would be better at HTHS than 20W50.

Mobil does not say HOW MUCH Zinc and Posphorous is in there. Is it 1200ppm or better?

I was giving a thumbs up to Tony when he said,

"It is OK to switch between syn and natural oil. I suggest, as would many others, to use Brad Penn 20-50."

I guess his statement contained 2 parts, the OK to switch and the recommendation to use BP. I wasn't necessarily endorsing BP as much as I was indicating that I've read over and over that switching will not cause any problems if the recommended weights are used. (Remember that the weights are different between the 2 types of oil.)

But, I was a fan of the old Kendall, so I would be a fan of BP.