I may have used the wrong engine oil

hello julia,
would be great to introdice yourslef and fill out your profile. this will help you to get answers and also will help the other members here
why you think you put in wrong oil? both are 20W50 castrol, so all ok.
how do you check the oil level? may be you did it the wrong way?

 

I wouldn't worry about the (slightly different) oil type. Did you use the correct method doing the oil level check? One other point is that you should target setting the engine oil level to be 1/2 way between the MIN and MAX marks (no need to be at the MAX mark, IMO, as it holds a huge amount of engine oil).

 

Fully synthetic oil is over-rated . Seriously, it was/is a fair bit of marketing malarkey that the manufacturers foisted on us to charge us a higher price (and is more important on my Honda to go 10K miles between oil changes). A couple of quarts of conventional oil in 16 total quarts is a non-issue IMO. Your using a 20W50 oil vs the TR spec of 10W40 oil is a much more significant deviation. (My preference is to use a 50/50 mix of Mobil1 10W40 and Mobil1 15W50 just to increase the ZDDP level back closer to where it used to be in oils when the TR was new.)

Always possible that the low oil level was just a miscommunication at the shop -- i.e., topping things up was left to a lower level tech and just got forgotten (I usually put about 8 quarts in it when doing the change and start the engine to check for leaks -- then top it up). You could be 3~4 quarts low in a TR and never notice a problem unless you were flogging it on a track. All you can do now is just keep checking it regularly to see if it stays the same or is decreasing rapidly.

 

This is what my factory tech uses. He’s been wrenching on TRs since they were new in 1984/5.

 

Not super-critical if in a non-freezing location, and a lot of F Owners use 20W50 successfully. Many recommended temperature range charts for 20WXX oil often list 0 deg C as the bottom end of the range.

 

Steve , what do you think about 5W40 instead of 10W-40 ? My view is that it’s thinner than 10W-40 and will circulate faster to give better lubricant and protection to the engine when car first started as compared to 10W-40 . And it will continue to thin out to reach about the same level of thickness as 10-40W when engine is hot .

( ps I come from a hot climate country and no winter )

 

Don't think that you'd have a problem with 5W40, but I'm no expert. Our resident "oil expert", AEHaas, has written a lot for bob is the oil guy so you could read his thread there (and the other related threads at the bottom of that thread):

https://bobistheoilguy.com/forums/threads/thin-vs-thick-discussion-chapter-1.339726

I'd summarize his opinion as: "In rational street use, your oil never gets hot enough to get too thin so most (all?) car manufacturers oil recommendation are much too viscous when at room temperature, and you're better off using as thin an oil as possible. Also, increasing flow (by using lower viscosity oil) gives better heat transfer". Consequently, using 5W40 instead of 10W40 fits well with his approach. What gives me some concern about this is that the load capacity and minimum film thickness of a journal bearing are proportional to the oil's viscosity so going too low (for the hot operating viscosity, not the cold start viscosity) could be a problem. However, I've not invested any real time in delving deeper so that's your homework .

 

Thanks Steve for sharing and I will go through the information .

 

I would not use such thin oil like 5 W 40. max down to 10 W 40 or 10 W 50, better 15 W 40 or 15 W 50. those cars are rarely driven in cold weather, so no need for such a thin oil. also, the thinner the oil the earlier it leaks. and as steve have written: the oil during normal driving will never get so hot that it will get too thin, even with 5 W xx

the synthetic oil 0 W xx and 5 W xx are good for automatic valve adjustment

 

How much oil sits in the filters? Maybe a couple of quarts? Not that familiar with the TR's....

 

Only one, slightly larger, oil filter on a TR -- maybe holds ~1 qt or a little more.