Motor Oil 106 (only 4 more chapters to go yet) Part Six. A personal recommendation. These are the motor oils I recommend. This is based on information that I just happened to collect. I have not gotten the specifications of all oils out there. My opinion on these oils is based on viscosities. By this I mean less honey like at start up temperatures and appropriate for the required viscosity at operating temperature. I broke it down to two classes, 1-Fully Synthetic and 2-Mineral (dinosaur) oils and blends of dinosaur and synthetic. The asterisk is my preferred from each group of very similar products. And these are usually easier to find in my experience. Remember, all oils are too thick at start up. There is no such thing as an oil that is too thin below 100F. The thinnest motor oil made is still too thick at start up temperatures. It seems that many engines work best with a multigrade 30 weight oil. Others would do better with a 20 weight oil and few would require a 40 weight oil. You can only determine what is best by experimenting. Admittedly I did not think my Ferrari Maranello would need a 20 weight oil. In truth I could actually use a 10 weight oil. A 0W-10 would be good but it simply does not exist for normal use. Red Line does make 2W, 5W and 10W oils (this acts as a 0W-10 multigrade oil) but they are for racing only. One Formula 1 team has actually used these very oils off the shelf from Red Line. . Synthetic Class: 60 wt: Redline straight 60 wt racing oil (racing only, acts as a SAE 20W-60 oil) Shell Helix Ultra Racing Oil 10W-60 Valvoline SynPower 20W-50* 50 wt: Castrol Syntec 5W-50* Shell Helix Ultra 15W-50 Penn Synthetic 5W-50 40 wt: Mobil 1, 0W-40* Shell Helix Ultra 5W-50 30 wt: Mobil 1, 0W-30* Penn Synthetic 5W-30 20 wt: Mobil 1, 0W-20* Valvoline SynPower 5W-20 . Non-Synthetic and synthetic blends: 60 wt: Castrol Syntec Blend 20W-50 50 wt: None recommended - all relatively too thick at start up. 40 wt: Penn regular Multigrade 10W-40 Valvoline Durablend 10W-40* 30 wt: Penn regular Multigrade 5W-30* Valvoline Durablend 5W-30 20 wt: Penn regular Multigrade 5W-20* Valvoline Durablend 5W-20 If while on the road you are forced to add oil there are rules. Let us say for example that our engine has synthetic Mobil One 0W-30. Use the same type and brand if you can. If you are using Mobil 1 then it is acceptable to mix different grades but use a close grade when possible. It is not a good idea to mix say 1/2 your oil tank with 0W-30 and 1/2 with 15W-50 Mobil One. If there is no Mobil 1 available then use mineral based oils next, preferably Mobil as first choice then any other name brand next. The last choice is to mix a synthetic of another brand. They specifically say this should not be done. I personally use Mobil 1, 0W-20 in the 575 Maranello and for the first oil change I drained the Murcielagos 5W-40 Agip and replaced it with 0W-30 Mobil 1. The engine became much quieter. A valve tappet noise disappeared. I may try the 0W-20 next. For all my other cars I use the regular Pennzoil Multigrade 5W-20. You have to try by experimentation what operating oil grade your engine requires. In all cases however, you want the oil that gets least honey-like at startup. aehaas Answers to the Oil Midterm Exam I feel these were all difficult questions. You would be doing well to get 3 correct. 1- At normal operating temperature, 212 F, a straight 30 weight oil has a viscosity of how many centiStokes? A- 3 B- 6 C- 10 D- 20 E- 30 The correct answer is C- 10 cS. 2- While racing at 95 F, mid-summer in Florida, which of these synthetic oils gives the best protection at 302 F oil temperature? A- 0W-40 B- 5W-40 C- 10W-40 D- Straight 40 weight E- They are all exactly the same The correct answer is E- They are all exactly the same. 3- While starting up your car at 75 F, mid-winter in Florida, what is the approximate viscosity of a straight 10 (ten) weight motor oil? A- 3 cS B- 6 cS C- 10 cS D- 20 cS E- 30 cS or higher The correct answer is E- 30 cS or higher. 4- The biggest problem with mineral based motor oils with long tern use is: A- Thinning B- Thickening C- Loss of VI (viscosity index) improvers D- Both A and C E- None of the above is correct The correct answer is B- Thickening 5- Which of the following mineral based motor oils are still too thick at a 75 F startup temperature? A- 20 weight B- 10 weight C- 5 weight D- All of the above E- None are too thick The correct answer is D- All of the above
I don't mean to be contentious (sp?) but why does Mobil say this about Mobil 1: Can different synthetic motor oils be mixed together? Mobil 1 with SuperSyn is fully compatible with conventional motor oils, semi-synthetic motor oils and other synthetic motor oils, should it be necessary to mix them. But the superior performance of Mobil 1 with SuperSyn will be reduced by diluting it. and AMSOIL says this: Are AMSOIL Motor Oils compatible with other motor oils? Yes. AMSOIL Motor Oils are compatible with all other synthetic or petroleum motor oils. You've mentioned before that you shouldn't mix synthetics, but why not, and why do these two make statements to the contrary? You've spent a lot more time than I have researching motor oils, so please fill us in on what's not obvious to the casual researcher, please!
Some of the literature of last year said not to mix them. One of the API / SAE requirements is that they must now be compatible. This still does not mean that you should mix them. It means that they should not have harmful chemical effects, by mixing them. The companies do talk to each other to make sure that things can be mixed. However, you will still be diluting additives if they are not the same type. One company may use detergent X and the other company detergent Y. If you mix the two oils 50-50 then each is at half the concentration and at that concentration they may not work at all or at least work less. The same can be said for each additive. Why would you want to start the oil out with each additive at half or at a reduced amount. Lastly the amount of information they give out gets larger as you research further. If you simply read the back of the can of oil it makes no mention of mixing oils. You have to read the full label, then the full specification sheet, the MSDS data sheets and others. While mineral oils are all of the same base oil (more or less), the synthetic oils may be of vastly differnet chemical structure. It makes sense not to mix more than you have to. Yes, you CAN mix them, but no they do not want them mixed. And if you have to mix them then use the order I specified earlier. aehaas
Is your "more or less" related to this Type I, II, III I've read about? I don't even remember if the classification was "Type" or not, but it was related to the base stock, and how much VI was required. What's the scoop there?
i have been reading these chapters with great intrest, but i do have a question.my owners manual calls out for Aquip Sint 2000 SAE 10w50, which is not available ( 1977 308GTB). shall i conclude its better to stay in the "10W" range and experiment with 10w40 or 10w30 oils? i am using currently using Castrol 10w40. my plan is to only run the car for 1000 miles or so and change the oil and Baldwin filter again. i used Mobile 1 15w50 in my other carb 308, but i am a bit confused by the "15w" versus the "10w" even though i have re read the previous chapters several times. comments please? Michael
I have not found any significance for different base types. As far as I am concerned as long as the oil is SL or SM rated it just does not matter. I do not know how much VI is used in the various formulas. Michael, I recommend the oils off the list for whatever grade you use and if you are only changing every 1,000 miles I may not spend the extra on synthetic oil. aehaas
AEHass, I am now using Mobile1 15w50 in my BB512i since the Agip Sint2000 10w50 is no longer available. Do you recommend I start using Castrol Syntec 5w50?
thanks. i guess i may just stick with the Castrol 10w40 since i have 2 cases of it, as i use it in my truck also. i am wondering if the car would like the 10w30 or Mobil 15w50, especially now that its winter time and a thinner oil may better. oh and thank you for sharing this with the world here, i can only guess as to how much of your time you have dedicated to this, for the good of the rest of us. THANK YOU!
My recommendations can all be read off the above chart, yes to the Castrol 5W-50. I recommend everything up there. aehaas
If you need a 50 weight oil I do not recommend the Mobil 15W-50. See the above chart for the oils I do recommend in each class. aehaas
How much does engine mileage affect these calculations? For instance, would Mobil 0-40 be appropriate for a 308 with 40,000 miles? Thanks for all your help.
Milage has no effect. You put in one oil and drive the car. You look at temperatures and pressures vs RPM. After the course is over you should be able to make an educated guess. If your engine was cared for as mine then there should be no wear. There are cars with 3,000 miles that are ruined. aehaas
Great info., please keep it coming... BTW, the Pennzoil 5w-50 is longer available...though they now show some additional weights, to include a 5w-40 and 5w-20, along with the common 5w-30 and 10w-30. Link below: http://www.pennzoil.com/products/motor_oil/full_synth.html Dave
BTW, a little factoid I'd forgotten all about! Castrol won the right in court to market highly refined conventional oil as "synthetic". Info here: http://www.1st-in-synthetics.com/articles7.htm http://www.1st-in-synthetics.com/newsletter_1000.htm Reprints from Lube World! Hosted by Amsoil.
Pennzoil may not have 5W-50 anymore but Quaker State does now. I don't know if it's a true PAO (or simialr) "real" synthetic or a "legally allowed to be advertised as a synthetic even though it came out of the ground just the same as any other oil" like domestically-produced Castrol Syntec, but since it was Castrol that started the practice, I choose to boycott them regardless.
WELL. Very informative. My 400i GT (Series II) also calls for Aqip 10W-50, which is not available in US. So I switched to Amsoil 15W-50. Also running 15W-50 Amsoil in my mint 1978 Porsche 928 (the car that made Tom Cruise famous!). Of course, these are full synthetics and after reading material here, I am considering Castrol Syntec 5W-50 in each. Engines are "perfect," with low mileage (32k Ferrari and 45k Porsche) from new, start, run and perform thru entire range perfectly (928 on race course once and performed without so much as a single "miss"). Note that both are low compression (8.8:1) engines! The other noteworthy item is that the V-12 takes 19.75 qts, 928 takes about 8 qts. We live in SW Virginia, moving to Aiken, SC, which is pretty low N. latitude (high normal average year-round temperature). Thanks in advance for your oil advice and recommendation(s), advice, and kind reply. Ed Trottier FOC/FCA/928OC
Any opinion on a 308 with Shell Rotella T synthetic 5w/40? I used this oil with great success in my 911s and it seems to have an incredibly robust additive package that I believe would be great for flat tappet engines as well. What is your opinion?
40W oil in a 308 will give you very low pressure at operating temperature. I would advise using 50 weight oil. Go to synthetic if you don't have leak worries. That way you can get a 5W or 10W for start up. If you don't like the leaks use the 20W 50 like most of us do. Or live with very low pressure if it doesn't bother you.
"Very low"? I used 40 weight synthetic in my 308 and 328 and never saw low oil pressure at operating temperature...all very normal. Is this a common experience, or specific to you?
40 weight oil at idle warm sits well below the first mark on my gauge. I consider this scary low pressure. Others may not. At higher rpm it of course moves to the center of the gauge, but personally it makes me feel uncomfortable.
I used 20w-50 Castrol dyno oil in my 3.2 911. When I made the switch to Rotella T synthetic 5w-40, I noticed no oil pressure difference once operating temp was reached, and oil consumption was noticably lower. One other noteworthy asset with this oil was the tiny oil leak I had in the engine was 100% gone when I switched to the Rotella T synt. I know Rotella T is sort of a group III (Shell's hydrocracking process is very unique), but the HTHS is very good at 4.1 as is the VI very high. The 308 might ('76) like it, but I do not want to use it until I get an expert opinion about the stuff for use in a Ferrari. After all, it was initially designed as a beefy deisel oil.
My current thinking is and I have multiple reasons for agreeing with AEHaas on the wisdom of true synthetic lighter oils. My belief was and is that film strength was vital for big end bearing and piston survival at elevated R.P.M.s. This is a concept that is proven over and again from truely stressed race motor engineering data. Now after having thrown that out there, I decided to put a test in place that would at the very least show me if my hunch was right or if I was fooling myself. I enlisted the help of a race engine builder who agreed to assist me in accruing additional knowledge of oils and their characteristics on the dyno. Stick with this as it gets very interesting. The motor in question was a roots type blown and stroked 500 + big block Chevy. This motor just happened to be the next in line to be tested and this was destined to be our oil test mule. He likes to break in motors with dino oils and his preference is Castrol 10W40 GTX, so he did a pull with this oil and recorded the results. We then dumped the oil and put in The same GTX with an anti friction additive (not what you think) that increased the viscosity to around 50-60 (no it wasn't STP or any of the other polymers) We then did another pull and the engine dropped 25 horsepower. Now here is the interesting part. Both oils showed virtually indentical power and torque readings all the way up to 6,000 RPM when dramatic things showed on the graph. The additivized oil spiked up to 62 psi oil pressure while the straight GTX dropped to 52 psi. At 6,000rpm they split and one went up and the other went down, the one that went down in pressure also produced the most h.p. What this is telling me is that frictional pumping losses were greater in the thicker oil or that peristaltic roping of the oil on the crank caused drag or that both happened simaltainiously. Now my next question is, Which oil protected better? It does offer up some concern when a oil suddenly drops pressue when it is at peak rpm and should be at optimum pressure. We will do the same test later with a different motor and some lighter synthetic with different oils and additives, my gut is that the thinner oils in true synthetic form with their higher film strength will produce the best results, but that remains to be seen.
So you've gotta tell us what the additive was ! My guess: Lucas. That's known to work great in a hand-cranked store display but get all crazy at actual engine operating conditions.