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Discussion Starter #1
Hi Everyone,
I have continued to use Mobil-1 15/50 over the years (not when they went to the gold top many years ago- I switched to Redline 15-50). Things are going well but I wanted to check if the Mobil 1 is still a good oil to use considering the age of an S4.

It is not like I keep up with how the companies keep updating formulas so I wanted to check-in and see what others are using.

Thank you.
Jason
 

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Wingless Wonder
1988 Esprit Turbo
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5,861 Posts
I still use Mobil1 15W-50, but since they changed it to SN specs, I add one container of ZDDP every other oil change (to protect the 'slipper' cam followers and cams).

I would use a ZDDP additive to ANY SN or SN+ grade oil. As an alternative, some folks use Mobil1 V-Twin 20W-50 (motorcycle oil) or Valvoline Racing 20W-50 synthetic.
 

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1993 Red Lotus Esprit SE
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21 Posts
I use Valvoline VR1 20W-50 dino oil in my 93SE. The previous owner had used Mobil-1. Don't recall viscosity he used, but I feel it was too thin. I recently switched my Porsche 924 to VR1 20W-50 dino oil from Castrol 20W-50.
 

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1986 Esprit Black/Red
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28 Posts
I am currently running Valvoline Racing 20W-50 fossil as I break in my new engine. Plan to switch to Valvoline Racing 20W-50 synthetic.
 

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Low viscosity has it's advantages as the oil gets circulating faster at cold starts. Oil pressure and oil flow are two different things and cold oil can show lots of pressure but not flow very well. The flip side is that when things are hot you need the higher viscosity to help maintain pressure. With regular oil the low viscosity is the "base" viscosity and it gets it's higher viscosity through the use of additives. Those additives break down (mostly through use, not time) leaving your oil performing more at the the lower rated viscosity. Synthetic oils are different in that they can be engineered to maintain their viscosity ranges much longer. Bottom line if you have an older or somewhat worn engine then a 20W-50 is probably going to be just fine and the 50 gives you lots of margin if/when the additives start to break down (especially important for a turbo). If your engine has tighter tolerances then 20W is going to be a bit heavy at cold startup, especially in cooler climates, so you're better off with a 10W-40 or even a 5W-40, but only if it's synthetic, or you change it religiously (which of course most of us do).
 

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1990 Esprit SE
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31 Posts
Hi Guys,
The 10w60 oils seem to have gained a lot of popularity for the 4cyl Esprit.
Mobil, Castrol and Valvoline are all contenders.
The "10w" giving you good flows on cold start and the "60" spec maintains strong oil pressure when the engine is hot.
(The oil pressure gauge reading can sometimes appear quite low during hot idle)
Seems good.

Andy.
 

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Hi all,
I currently have valvoline 10w60 VR1 Racing. Engine is still running in, but all seems to be fine, with a near constant pressure at start up and when sat in traffic.

thebartman
 

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The best advice is to use what the manufacturer recomends for the temperature range you expect to operate in. Synthetic is good but if your engine was broken in and "raised" on regular oil, it may leak more on synthetic. As for ZDDP or "zinc" additives, if the engine was broken in and used regular oil (old blend with higher levels of ZDDP) the metal gets "conditioned" and doesn't require high levels of ZDDP anymore. The problem with additives is that if you overdo it you can have negative effects. Unless you are a chemist and know what the level of ZDDP is you could have way too much and that would be bad for your catalytic converter. Instead of additives, you are probably better off just changing the oil more frequently so you always have a 'fresh" additive package. Oil doesn't go bad (unless it gets burnt) so much as it gets dirty and the additive package gets used up. Because most of our Lotus's don't rack up a lot of miles anymore, changing the motor oil once a year is plenty.
David Teitelbaum
 

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The story about changing to synthetic oil causing leaking on older engines due to it somehow cleaning or affecting the seals or gaskets is basically urban myth. Yes, syn oil does sometimes leak more but it's due to the better flow rate at low temps - basically when the engine is cold. If you already have leaks you may see them leak more with syn oil, especially of you use a lower viscosity, but to me it's a fair trade (these are British cars after all) in favor of the additional engine protection.
 

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The metalurgy of Lotus 9XX engines, including the V8, is pretty ordinary stuff. Cast iron cams, tappets, cylinder liners, crankshaft... with no special anti-wear treatments or coatings. The engines depend heavily upon the higher PHOSPHORUS levels that were common in motor oils of the day. ZDDP is just the most common additive used to introduce phosphorus into the soup. You don't need any ZDDP "IF" you can get the required phosphorus levels by other means. With reduced levels of phosphorus in modern oils, you must be very selective about what oil you select.

As a general rule, don't put an oil with less than 1200 ppm PHOSPHORUS in your Lotus engine. That applies to every Lotus engine from the Mk Six through the Esprit V8. The modern Toyota powered models are a different matter.

The following list is the oils available in North America that I like. Note that there is less phosphorus in ZDDP than there is zinc. In order to achieve the amounT of phosphorus indicated below, the ZDDP level will need to be higher than that level.

Parts Per Million (ie, 1000 ppm = 0.10% = 1/10 of one percent)
.Phos. / Zinc
2400p / 2500z Redline Racing Motor Oils (typical, “all have a min. of 2200 ppm Phos”)
2100p / 2500z Redline Motorcycle Oils
1750p / 1850z Mobil 1 0W-50 Racing Oil (contains full street additive package).
1600p / 1700z Mobil 1 20W-50 V-Twin Motorcycle Oil (good stuff)
1400p / 1500z Brad Penn®, Penn Grade 1 Hi-Perf Oils
1300p / 1400z Valvoline VR1 Racing Oil (mineral oil), API SF/CD.
1300p / 1400z Valvoline VR1 "Not Street Legal" Racing Oil (no street additives)
1266p / 1379z Amsoil ARO 20W-50 Synthetic, street, gas/ Diesel, for API SL/ CI-4 Plus
1200p / 1300z Mobil 1 15W-50.
1200p is the minimum phosphorus level I will put into a Lotus engine that is already broken in. That's just my opinion.

If an oil company will not tell you how much phosphorus is in their oil, then do not use that oil. When they say, "Trust us"... don't.

Note that the Redline, Mobil 1 and Valvoline VR1 racing oils contain full street additive packages, and are safe to use on the street. They're "boutique racing oils" that are really just a backdoor way to get around the API and sell the high ZDDP oils car guys like us need.

On the other hand, Valvoline VR1 NSL (Not Street Legal) is a real racing oil, and contains NONE OF THE STREET ADDITIVES required for long change intervals NSL will protect your engines bearings and wear surfaces, but if you used it in a street car, then you must change it every 500 miles or 3-months, whichever comes first. That recommendation comes from Valvoline.

Use a xxW50 or higher viscosity oil. 10W60 would be great, as long as it also has a phosphorus level of 1200 ppm or higher... preferably more.

Note that back in the day, Mobil 1 used to sell a 20W50 synthetic automotive oil that was very good for the Lotus engines, and Lotus recommended it. However, it contained more phosphorus (ZDDP) than the API allows for use in automotive engines. So Mobil 1 has simply changed it's name to 20W50 V-Twin Motorcycle Oil. It's the same great stuff, and my personal preference for Lotus engines. Mobil 1 also sells a 10W60 synthetic in Europe that would be very good if you can get it. I'm jealous.

Atwell, you mentioned using Mobil 1 15W50 along along with a ZDDP additive. That's one way to go, but you don't really know if you're getting the correct 'balance' of additives needed. An alternative would be to use Mobil 1 0W50 Racing Oil (1750ppm phosphorus) instead of an additive.

.Phos. / Zinc
1383p / 1483z 3 Qts Mobil 1 15W-50 plus 2 qt Mobil 1 0W-50 Racing Oil
1310p / 1410z 4 Qts Mobil 1 15W-50 plus 1 qt Mobil 1 0W-50 Racing Oil

The oils are from the same family, they're perfectly compatible, and you know the additive balance is correct.

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Use xxW50 or higher viscosity oil. Do not use lower viscosity oils. Plain bearing design (mains, rods, cams) depends upon a balance of bearing clearances, oil pump pressure & flow capacity, and oil viscosity. The design engineers made some choices without asking for your opinion first, but it's done. And all Pre-Toyota Lotus engines have wide bearing clearances, modest-pressure/ high volume pumps, and require higher viscosity oils... xxW50 or higher. You can be insulted that they didn't ask you first, but it's done. Do not put modern low viscosity oils in your Lotus engines... not even 10W40. Or, do it. And the rest of you, please do not follow that poor soul down that path.

Regards,
Tim Engel
 

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Discussion Starter #11
Thank you for all the replies. The information shared is excellent and much appreciated Tim for that level of detail. I definitely now have an idea of what to look for.
 

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I just thought of one more consideration when choosing a motor oil. The typical detergent in older oils was based on sodium, and sodium is one more element they're now trying to eliminate or minimize in motor oil. Many modern oils are using calcium based detergents instead, but calcium is not as compatible with phosphorus (ZDDP).

As a result, a modern oil with higher calcium content requires more phosphorus to give the same level of anti-wear as an older oil with lower calcium content. You can't simply compare the phosphorus levels of two oils, older and new. For the same phosphorus level, a modern oil with higher calcium content will not protect your vintage engine as well.

That's one more reason why it's important to know what is in an oil before choosing to use it. If an oil company won't tell you what's in their oil (most won't), then don't use their product. Turn-about is fair play.

Regards,
Tim Engel
 

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Wingless Wonder
1988 Esprit Turbo
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<SIGH> I have a headache now. :rolleyes:
 
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Atwell, you forgot to read the ABV of the beer you were drinking. That is the root cause of your headache.....I am sure!!!!!
 

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The EPA is trying to reduce the heavy metal content in motor oils to extend the life of the catalytic converters. Over time they get contaminated by the metals and they fail. The EPA wants to see cars that can pass the emissions standards under which they were built for 100,000 miles. This is why you are seeing oil companies rebranding and changing what they sell. Anecdotally there is a lot of evidence that a motor "weaned" on high ZDDP content oil gets "conditioned" and doesn't need such high levels after a while. Some owners use additives to try to achieve higher ZDDP levels. The problem is you really don't know what your actual levels are, how compatible your additives are with your oil, and what other changes are affected by the additive. The best solution is not to use additives but to find the best oil that has been engineered to work in your motor. The highest wear area in your motor is the cams and lifters. Watch them and then you will know how your oil is doing. One way to do that without taking the motor all apart is to measure and watch valve lift. The other thing you can do is change your oil often. The additive package wears out so putting in fresh oil gets you the highest level of additive package.
David Teitelbaum
 
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