Shell 10W60

Now let us consider that many oil companies indicate that use of oil at 285 or even 300 degrees F is NOT subjecting the engine to excessive rates of wear <e.g.>. This gives us an important clue.
So lets go back to the viscocity graphs and place another marker at 285 <the> and see what viscicity the engine oiol is operating at:

Now let us consider that many oil companies indicate that use of oil at 285 or even 300 degrees F is NOT subjecting the engine to excessive rates of wear <e.g.>. This gives us an important clue.
So lets go back to the viscocity graphs and place another marker at 285 <the> and see what viscicity the engine oiol is operating at:



I used a 10W40 oil and placed a marker at 285 degrees F as this corresponds to the recommended oil for an F355.

Note: there is a change in measurement technique for the hot test point and this results in the slight break in the slope of the line not some curveature of the viscocity with respect to temperature.

This tells us that the engine is perfectly happy and well protected with an oil with a viscocity of 4 at 285 dF.

I note that all of the 40 weight oils have 4 or almost 4 as their viscocity at 285 dF, so this tells us we are on to something. Now let us look back at lighter weight oils suggested by Ali:



Not all of the 30 weight oils has sufficient viscocity at high temperatures, BUT SOME DO. Two things begome evident at this point, for those drivers who never see the far side of 250 dF in their oil, any of the 30 weight oils are fine for protection. For those who do see the far side of 250 dF, carefully chosen oils are perfectly adequate to protecty you engine even under track use conditions.

As further evidence that this makes sense, I present the data for a Mobil 1 5W40 and for shell helix 10W40 <since M1 most closely match the numbers for the shell oil)

Ali's point to light weight oils is based on the evidence that oil experts around the net say that 'most' of the wear on an engine occurs during the first few minutes after startup. This being the case, getting the oil flowing is vitally important, and lighter weight oils simply flow faster, and start lubricating faster.

The diatribe leading up to this opoint shows that any oil thicker than 4 cSt at 285 dF is thick enough to protect your engine. What is not yet apparent is that any oil thicker than 15 <or> is vastly thicker than necessary to protect and lubricate. It just so happens that no oil can <yet> be manufactures that has such a low cold viscocity and such a high hot viscocity.

However, going towards lighter weight oils is a viable mans to attack startup wear and if the oil is carefully chosen (by the measurement numbers not by the classification schems) then even thinn oils are acceptable at track events.

I, myself, have been running an experiment at the track in hot Texas summer weather (TWS for those curious). Using 15W50 Mobil 1 I was routinely exiting the track with 285 dF oil temperatures, had 35 PSI at idle (still at 285 dF), and 70 PSI by 2500 RPM. Switching to a 10W40 RedLine oil dropped the track exit temperatures to 265 dF and raised the idle oil pressure to 45 PSI. In addition, the water temp was every so slightly lower. Both datapoints were from multiple runs over multiple days and never less than 15 laps of TWS (2.9 miles/lap). Oil consumption went from 0.3 Quarts per track day to 0.6 per track day.

Ali thinks that the thinner oil has lower pumping losses and thereby absorbes less heat by being pumped through the oil pump. All I can relate is my track experience substantiates this position and the engine felt as if it wer perfectly happy with the thinner oil.

Which bring me to my last chart:



Here I place another marker showing the fully warmed up temperature of my F355 (just under 200 dF) and we find that the Ferrari recommended oil is just above 10.7 cSt. This substantiates the notion that any oil thicker than <say> 15 cSt is too thick or at least you should not place a heavy load on the engine until the oil really does ge twarmed up.

Enjoy.

I forgot this a while ago::

Some of the oils have a special relationship with respect to temperature. They stay retain a lot of viscocity in the HTHS test that is greater than the more typical oils. These are plotted on the following:


Using any of these oils <and> and one is protected to >4 cSt at 285 dF.

These oils are especially important for real race use, which is considerably harder than typical track driving use as A) you can't stop if the oil gets hot and expect a favorable race outcome, B) If/when you are subject to excessive oil temperatures, the lower angle of viscocity with respect to temperature means the heavier of these oils will protect the engine well into the low 300 dF range (viscocity wise), C) race engines do not have 100,000 mile warentees and are rebuilt regularly so startup wear is not as important as on street cars.

I found this data about my track oil data::

This shows that both oils are way above the standard rule of thumb (10 PSI for every 1000 RPMs). Since we reach the point where the oil pressure regulator pops off under 3000 RPMs, the added energy used to compress some oil that is released by the pop off valve absorbes energy from the engine operations but does NOT add to the oil flowing around the engine. Therefore, it saps power from the engine and does not useful work.

Mitch,

You rule!

Very interesting, thanks.

Mitch, you are unbelievable. Bottom line, what oil would use in a 1988 328 that is not driven on the track, but just a an occasional driver. Also, I have an unopened case of Sint 2000 10/40 that is about 4 years old. Does it degrade with time?

I would think it degrades..but more importantly, oils have improved significantly in the past few years....what is the API rating? SH? SJ? The latest oils are now rated SL. FWIW

"Bottom line, what oil would use in a 1988 328 that is not driven on the track, but just a an occasional driver."

What does the oil temperature guage read? If it never gets over 250 dF then you will be fine with xW30 of any modern synthetic. This oil may be so thin that oil consumption goes up and the consumption issue drives you towards thicker oil. Over in Europe they have 0W50 oils that many are having luck with these days. My next change is going to be a 5W40 oil AMSOil developed for European driving conditions. For more typical driving conditions, the 4-ball wear scar test is more indicative of wear protection than the weight of the oil.

Then there is the old wives tale of the Viscosity improvers (that increase the spread between the number infront of the 'W" and the number after the 'W') having low shear strength. Modern VI oils have excellent ratings on tests designed to ferret out whether the shear strength is adequate. See the HTHS oil rating on the data sheet.

"what is the API rating? SH? SJ? The latest oils are now rated SL."

API rating is "junk". Get the oil data sheets and construct the oil database as I did above. But do look at the 4-ball wear scar test, and if you track the car look at the HTHS number.

I am a firm believer that thinner oils are better for startup (wear protection), and if the temperature guage never gets above 250dF, the thinnest oil you get reasonable oil consumption. Also note (strongly): there are 0W30 oils that are closer to -5W25 and there are 0W30 weight oils that are closer to 5W35 weight oils. The only way to tell (if you are pushing the viscocity towards thinner oils) is to look up the actual data from the web sites, you cannot look at the xWyy numbers in the store and make reasonable choices, and the API ratings are so wide that many oil companies make huge batches of oils that straddle the boundaries between 5W30 and 10W30. If a batch comes out too thin, it is sold as the thinner designation, if its too thick, as the other, most batches can be sold as EITHER.

Many may have noticed that NASCAR race engines are now using 0W30 oils and some even 0W20 oils for race day. One of the changes to utilize these oils was the increasing of the oil cooling radiator area and a drop from 280 dF oil temps to 250 dF oil temps to keep the viscocity in a more reasonable range. This 30 dF drop increases the oils viscosity (in abosulute terms) back to where the old (thicker) oils ran. These engines are also clearanced for and the oil pump capacity specified for the flow rates of these thinner oils.

The oil temperature guage is the key to avoid getting this wrong. Thin oils have many advantages, however, you have to do your homework.

Hi I am new to this forum and wanted to ask another question regarding engine oil. I just bought a 328 and would like to change oil to synthetic(mobil 1). Not sure what type of oil was used previously(I think it was regular). Is the proper procedure to drain the oil refill, run engine and then drain again and change oil filter and refill with new?

Also have another question reagrding gear oil. Had a chance to check the level of gear oil when the car was up on a rack. Found a green oil and also found that it wsa filled much higher than the bottom of the filler hole. Will that effect the difficulty in changing gears(as most ferrari owners (I think mine) will not shift in to second when cold)? What kind of oil should I use to replace the gear oil?

Thanks
Z