Oil - Regular vs. Synthetic

[Musicman]

Greetings!

The next time my oil and filter are due for a change I'm thinking about going with synthetic oil, Mobil 1, 10W-30, to be precise. I know that a lot of the "synthetic" oils out there are not 100% synthetic. Mobil 1 is.

What type and grade(s) of oil are you guys using in your TR's?

All input is welcome.

Thanks!

 

[AltaKnight]

You're right Mobil 1 is one of the few truly synthetics and a great motor oil.
A word of caution though, these cars weren't designed for synthetic oils, if your car leaks oil now (and they all do) then the synthetic oil may make your drive look like the Exxon Valdiz visited it. /ubbthreads/images/graemlins/shocked.gif
Also, and probably more important, the low viscosity of the oil might drop your oil pressure significantly depending on your engine wear.

 

[machinemd]

Here's an excellent write up on oil. The Boss 302 title only refers to his toy of choice.

https://www.boss302.com/oil.htm

Steve

 

[sammyb]

I used a blended synthetic in my TR3 and didn't notice much difference in any respects. I probably wouldn't use Mobil 1 in the TRs, but I do use it in my Corvette (as the factory specifies.)

 

[achtungeveryone]

I would not use it in my tr6 (and it luckily doesn't leak) but I do use it in an 01 truck. I think it would cause more trouble than good in the 6.

Achtung

 

[Musicman]

Okay, so far it seems that traditional oil is the way to go for the TR6. What weight ranges are you guys using? If I remember correctly years ago I used to use 20W-50 all year long (I lived in NY at the time).

Thanks!

 

[SCguy]

It's still Castrol 20-50 for me.

 

[Bugeye58]

Castrol 20W50 here too. Back in the day when I was running an LBC year 'round, here in Mi., I would switch to 10W30 in the winter. It made the little beastie a bit easier to start when the temp dropped into the ridiculous range.
Jeff

 

[Musicman]

Jeff,

I was actually thinking about going with a 10W-30 for the winter months here. It rarely gets below 5 degrees or so here. Do you think I should go with the 10W-30 for the winter and then switch to the 20W-50 for the spring and summer?

Thanks!

 

[jerrybny]

I only drive my TR6 from late spring to fall so I always run Castrol 20W-50.

 

[Bugeye58]

Dave, I would run 10W30. It not only makes starting a bit easier but I would imagine the oil flows to the bearings a tad quicker.
Looking at my GT6 book, (the only 6 cyl. reference I have handy), it recommends 10W30 below 30F.
You certainly won't hurt anything by running the lighter oil in colder temps, and switching back to 20W50 when things get warmer.
Jeff

 

[Musicman]

Jeff,

Thanks for the insight. That's exactly what I'll do. For winter, 10W-30 and 20W-50 for the warmer times of the year.

 

[Bugeye58]

My pleasure, Dave. If you have the owners manual, it should specify the oil requirements vs temperatures.
Jeff

 

[Alan_Myers]

[ QUOTE ]
That's exactly what I'll do. For winter, 10W-30....

[/ QUOTE ]

Hi Dave,

Hmmmmm, the old dino vs. synthetic oil question raises its head again!

One thing not yet mentioned... Don't be surprised if your car begins to consume some oil, possibly providing a smoke screen out the tail pipe, or even start fouling plugs. Due to its slipperier nature, synthetic oil is more likely to get past the rings into the combustion chamber. This will especially be true if you go as light as 10w30 and is more likely on an engine that's got some higher miles on it, i.e. has an acceptable margin of wear and a little bit larger clearances.

One positive feature of synthetic oil is that it's less subject to thickening in colder weather, as well as less inclined to thin at higher tepms. In other words, it's viscosity is more stable at both low and high temps. You might get by with a heavier grade in the cold months, if you really have your heart set on switching to synthetic.

Whenever this topic comes up, I feel it's *very* important to note that synthetic oil should *never* be used in a freshly rebuilt engine. If that is done, there's a good chance some of the rebuild will need to be done over again. The slipperiness of synth will prevent the rings from bedding into the cylinder walls, probably will cause glazing on the cyl. walls and the engine will never see full potential due to lower compression, plus will likely always excessively burn whatever oil is in it. Most guidelines say to stick with dino oil for the first 6000-9000 miles on a fresh rebuild, to avoid these sorts of problems.

Another thing, many synthetics are formulated with a lot of detergents. A clue to this is the "high mileage" rating of most, perhaps to help consumers justify paying the 2x the price and offering the convenience of double or even triple the normal oil change interval. I can't say from personal experience with the 6-cyl., but the 4-cyl. engine needs a bit of coking to properly seal and perform well. In other words, the motor is designed to run some build up. Remove it with a lot of detergents and, again, there is an increased chance of poor cyl. sealing problems.

So, it's just my opinion, but I think straight synthetic oils are a waste of money in these older engines and actually might do as much harm as good. I'll stick with non-synth Valvoline or Castrol 20w50 most of the time here in N. Calif. where the temps are pretty mild. When I lived in Colorado, I switched to 10w40 in the winter. Or I'd go with half and half 20w50 and 10w40 in cooler, but not really cold months, or even in the dead of winter with an engine that's got a lot of miles on it.

/ubbthreads/images/graemlins/cheers.gif

 

[Musicman]

Alan,

Thanks much for info. I've decided to go with dino, probably Castrol. Being that it's winter time here (cold weather yet to come) would it make any difference going with the 10W-30 or the 10W-40?

 

[Alan_Myers]

[ QUOTE ]
Being that it's winter time here (cold weather yet to come) would it make any difference going with the 10W-30 or the 10W-40?

[/ QUOTE ]

Hi Dave,

I think it sort of depends upon the wear in the engine, i.e. how many miles are on it since it's last rebuild.

If the manual calls for 10w30 in colder temps, I would have to assume the manufacturer's recommedation is based upon a fresh engine with no significant wear and tear. An engine with some miles and a little wear might be better using slightly heavier 10w40, or even mix a couple quarts of each for something in between.

/ubbthreads/images/graemlins/cheers.gif

 

[Musicman]

Alan,

The engine has less than 30,000 miles on it. I think I'll go with the 10w40 for this time of year. I'm sure 10w30 would work also, but I figured since there's some mileage already on the engine I figured I'd go with the 10w40. When it warms up come spring and summertime (I can't wait) I'll switch to the 20w-50.

 

[vettedog72]

Alan
For waht its worth, I had bad experience with Castrol in a 240DL Volvo. It was not the same weight used in the Triumph but it was the same brand just a thinner oil. One problem was a residue deposited through out the engine. Also one oil galley filled up with carbon and caused the cam to size. I realize that era of 240DL’s had oil galley problems but it still happened with frequent oil changes (instead of the 6000miles recommended by the mfg)and I hold poor oil compatibility responsible. I did not see inside with my own eyes except the area I could see through the oil filler in the rocker/cam cover. The TR6 faired a little better with just brownish residue but I had a good bit of sludge/carbon build up in the area under the valve cover and sludge in the oil pan in spite of frequent oil changes that seldom exceeding 3000 miles over 60,000 miles. I have a Chevy 350 with over 300k miles and I have used Castrol Syntec BLEND for the past 200,000 miles with great results. The engine has remained fairly clean and still runs 3000 miles w/o burning a quart. I intend to use Castrol Syntec Blend when I get (if I ever get) 5000 miles on the TR6 at a higher viscosity than the 10W30 used in the Chevy. Long live the SynTec Blend.

 

[Bugeye58]

Vette, my 740 Turbo wagon has had nothing but Castrol 10W30 in it for all its 171000 miles, and the inside of the cam cover is as clean as a whistle.
Go figure.
Jeff

 

[Alan_Myers]

Hi all,

There aren't any one-size-fits-all answers when it comes to motor oil, I'm afraid.

I generally use Valvoline oils, myself.

I do use a synthetic blend in "modern" daily-driver engines. Modern engines tend to run hotter and often have closer tolerance manufacturing. (Examples include a '97 Land Rover and a '94 Pontiac, currently. VWs, Toyotas, Nissans and others in the past. Yeah, I know the LR engine is a 1950s GM/Buick design, hardly modern. But I consider and treat it as modern based upon current manufacturing methods plus modern function and control.)

I've tried full synthetic. But have seen a few new leaks, some oil burning and have had two different engines develop noisy hydraulic lifters when using it (at cold start, both were low mileage, but fully broken in). It did give noticibly better gas mileage in one case, which I can only assume was due to decreased friction. Oh, and I ruined an oil-bathed clutch in a motorcycle, when I accidentally poured in a quart of full synth oil!

Heavy build-up within an engine might be oil related, or it might not. I'd look at the PCV valve and/or any other crankcase breathers for the most likely culprit. Also, a leak-down compression test might find rings and/or valve guides are "passing some gas". I don't claim to know much about Volvos, though!

Most "street" motor oils have some detergent additives to help prevent sludge build up, in varying degrees. It's hard to get specific info, though. Each manufacturer keeps their cards pretty close to their chest. ("Racing" motor oil is nearly always non-detergent but really requires very frequent changes - weekly/every few hundred miles - so should probably be avoided in street cars. I put racing oil in TR gearboxes, where I don't want detergents because it causes foaming and there aren't any combustion gases to deal with.)

In my earlier response, I was simply saying that many full synthetic oils have a lots and lots of detergents, maybe three or four times as much in "extended mileage" oils, and possibly way too much for older engines that need a little varnish or coking to seal well, particularly around the rings.

A good-quality dino oil and 3000 mile oil changes still get my vote for the TR. I will not use recycled or no-name oils, although I know many who do and report all is well with their engines.